Notice of Annual General Meeting of Shareholders

We are pleased to invite you to join the board of directors (the “Board” or the “Board of Directors”) and senior leadership at the Aon plc (“Aon” or the “Company”) annual general meeting of shareholders (the “Annual Meeting”) scheduled for Friday, June 27, 2025, at 8:30 a.m. Irish Standard Time.

Items of Business:

Shareholders are strongly encouraged to vote their shares by proxy in advance of the Annual Meeting by one of the methods described on pages 95-96 of the proxy statement. Shareholders who wish to attend the Annual Meeting virtually may do so via webcast at meetnow.global/MDCGLRH, as further described on page 97 of the proxy statement. Note that attending the Annual Meeting virtually will not allow you to vote at the Annual Meeting. During the Annual Meeting, the Board will present, for consideration by the shareholders, the Company’s statutory financial statements under Irish law for the fiscal year ended December 31, 2024 (including the reports of the directors and the Irish statutory auditor thereon), and a review of the Company’s affairs. We urge you to read the attached proxy statement for additional information concerning the matters to be considered at the Annual Meeting. The proxy statement shall be deemed incorporated into this notice.

Holders of Class A Ordinary Shares at the close of business on April 11, 2025, can vote at the Annual Meeting. A shareholder of record entitled to attend and vote at the Annual Meeting may appoint one or more proxies to attend, speak, and vote on his or her behalf by any of the procedures set out below and on pages 95-96 of the proxy statement. A proxy holder need not be a shareholder of record. To be valid, a proxy must be received by the Company using one of such procedures no later than 5:00 pm (Irish Standard Time) on June 26, 2025 (or in the case of an adjournment or postponement thereof, such later time as may be announced by the Company not being greater than 48 hours before the adjourned or postponed meeting), the proxy deadline.

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting of Shareholders to be held on June 27, 2025.

The proxy statement, our Annual Report for the fiscal year ended December 31, 2024, and our Irish financial statements are available at www.envisionreports.com/AON. This notice and proxy statement are first being mailed or made available to shareholders on or about April 28, 2025.

By Order of the Board of Directors,

Darren Zeidel

Company Secretary

April 28, 2025

Your vote is important

Only holders of Class A Ordinary Shares as of the record date April 11, 2025, can vote at the Annual Meeting. Please cast your vote as soon as possible in one of the following ways:

If you are a beneficial owner, you should follow the directions provided by your broker, bank or other nominee. You may submit instructions by telephone or through the Internet to your broker, bank, or other nominee, or request and return a paper proxy card to your broker, bank, or other nominee.

Proxy Summary

Voting Matters

Shareholders are being asked to vote on the following matters at the Annual Meeting:

We are providing the enclosed proxy materials to you in connection with the solicitation by the board of directors (the “Board”) of Aon plc (“Aon” or the “Company”) of proxies to be voted at the annual general meeting of shareholders to be held on June 27, 2025 (the “Annual Meeting”), or any adjournment or postponement thereof. The Annual Meeting will be held at 70 Sir John Rogerson’s Quay, Dublin 2, Ireland. This proxy statement is first being mailed or made available to shareholders on or about April 28, 2025.

2025 Aon Proxy Statement  1

Aon is in the Business of Better Decisions

Aon exists to shape decisions for the better — to protect and enrich the lives of people around the world. Through actionable analytic insight, globally integrated Risk Capital and Human Capital expertise, and locally relevant solutions, our colleagues provide clients in over 120 countries with the clarity and confidence to make better risk and people decisions that protect and grow their businesses.

Our 3x3 Plan – with a focus on three commitments over three years (2024-2026) – is enabling Aon to go further, faster to address client need:

Through our 3x3 Plan we will accelerate our Aon United strategy to deliver critical outcomes for clients, colleagues and shareholders.

Our Solutions

We are a leading global professional services firm providing a broad range of Risk Capital and Human Capital solutions. Through our experience, global reach and comprehensive analytics, we help clients meet rapidly changing, increasingly complex and interconnected risk and people challenges.

Corporate Sustainability and Risk

Management of corporate sustainability risks – including those related to environmental, social and governance (“ESG”) matters – is an increasingly important priority for our clients. At Aon, helping clients manage risk – including those relating to corporate sustainability and ESG – is at the core of what we do. We offer a wide range of risk assessment, consulting, and advisory solutions, many of which are significant parts of our core business offerings, designed to address and manage corporate sustainability and ESG issues for clients, and to enable our clients to create more sustainable value.

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As a professional services firm, Aon’s approach to risk management, including oversight of corporate sustainability and ESG risks, is a priority. The Board, as a whole and through its committees, oversees the Company’s ESG risks and opportunities, as well as related strategies, goals and objectives, and performance. The Board regularly reviews and discusses our ESG risks and opportunities, including Aon’s decarbonization and sustainability efforts and people-related risks, such as colleague satisfaction and engagement survey results, workforce engagement, pay equity, colleague well-being, talent retention and succession planning. We are committed to improving inclusion and wellbeing at Aon at all levels of our organization and have published certain of our workforce demographic data in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024. Our EEO-1 Employer Information Summary Reports are available on our website at www.aon.com. Our Board is committed to continued adherence to effective corporate governance best practices, including oversight of enterprise risk management.

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2024 Highlights

In 2024, we continued to deliver across these four metrics:

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Our Board of Directors

In August 2024, we announced that Admiral James Stavridis joined our Board effective August 15, 2024. Admiral Stavridis serves on the Finance Committee of the Board. On April 10, 2025, we announced that Fulvio Conti will be retiring from our Board effective at the Annual Meeting. Upon Mr. Conti’s retirement, our Board will be composed of 12 directors, 11 of whom are independent, including the Board Chair. It is a priority of the Governance/Nominating Committee to identify candidates for the Board of Directors who bring to our Board a wide variety of experiences, skills, qualifications and perspectives that strengthen their ability to carry out their oversight responsibilities.

Our Governance/Nominating Committee also considers a number of demographic and other factors in seeking to develop a Board that, as a whole, has the appropriate background, skills and experiences in the context of the needs of the Board.

As part of our ongoing Board refreshment process, we welcomed two new independent directors in 2024, four new independent directors since 2022, and seven new independent directors since 2016.

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Directors

* Independent director

^† Number of current other public company directorships or listed business development company trusteeships

^†† Mr. Conti is retiring effective at the Annual Meeting.

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Corporate Governance Highlights

Aon’s commitment to good corporate governance is integral to our business. Highlights of our strong corporate governance practices include:

2024 Executive Compensation Highlights

The core principle of our executive compensation program continues to be pay for performance, as we continue towards our goal of being the leading global professional services firm focused on risk, health, and wealth.

Leadership Performance Program. In early 2025, we settled performance share units (“PSUs”) granted to our NEOs in 2022 under our seventeenth LPP cycle (“LPP 17”). The settlement of those units in Class A Ordinary Shares was contingent upon achieving adjusted diluted earnings per share of at least $38.20 (threshold performance) over the performance period from January 1, 2022 to December 31, 2024, and reflects achievement of adjusted diluted earnings per share of $42.12, which exceeded the target performance level adjusted diluted earnings per share of $39.72. In 2024, we granted PSUs under our nineteenth LPP cycle (“LPP 19”) to each of our NEOs, which are expected to be settled in 2027 contingent upon the Company’s adjusted diluted earnings per share growth performance over the January 1, 2024 to December 31, 2026 performance period.

Annual Incentive Compensation. Annual incentives paid to our NEOs reflected our application of the incentive pool funding framework adopted by the Organization and Compensation Committee (the “Compensation Committee”), as well as the committee’s evaluation of each NEO’s contributions to our business and financial results, delivery of key strategic initiatives, and personal leadership qualities. The incentive pool funding determination included both a pre-established formulaic financial component (80% weighted), based on comparison of current year adjusted operating income results against the prior year, and a non-formulaic People & Culture component (20% weighted), based on Company’s progress across four areas: wellbeing, inclusion, engagement, and retention. Target annual incentive opportunities for our NEOs for 2024, as a percentage of base salary, remain unchanged from 2023. Once determined, annual incentives to our NEOs (other than Mr. Case) were paid 65% in cash and 35% in the form of time-vested restricted share units, which provides value to our executives that is tied to the long-term performance of the Company. Mr. Case’s annual incentive was paid 65% in the form of cash and 35% in the form of performance share units under our twentieth LPP cycle, as a further tie to the long-term

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Compensation-Related Best Practices

performance of the Company. Annual incentives for 2024 were awarded to our NEOs in early 2025 following the Company’s achievement of adjusted operating income of $4,939 million. The annual incentive awards are described in more detail in the section captioned “Annual Incentive Awards Under Our Shareholder-Approved Plan” below.

Our compensation philosophy and related governance features are complemented by several policies and practices designed to align our executive compensation program with the long-term interests of our shareholders, including the following:

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Proposal 1 — Resolutions Regarding the Election of Directors

What am I voting on?

The current members of the Board, other than Fulvio Conti, are standing for election, in each case to serve until our 2026 annual general meeting. The 12 directors who are standing for election are named below.

The Governance/Nominating Committee of the Board (the “Governance/Nominating Committee”) has recommended to the Board that each director be nominated. With respect to Mr. Case, his employment agreement provides that he will be nominated for election as a director at each annual general meeting of shareholders during the period of his employment. All nominees for director have consented to being named in this proxy statement and have agreed to serve as directors if re-elected. We have no reason to believe that any of the nominees will not be available to serve as a director. However, if any nominee should become unavailable to serve for any reason, the proxies may be voted for such substitute nominees as may be designated by the Board, or the Board may reduce its size.

The term of each director expires at the next annual general meeting of shareholders, and each director will continue in office until the election of his or her respective successor or until his or her earlier resignation or removal in accordance with the Company’s articles of association (the “Articles”) or the Irish Companies Act 2014, as amended (the “Irish Companies Act”). Consistent with the terms of the Articles, the Board currently is authorized to have up to 21 directors, and the number of directors was most recently set by the Board at 13. Fulvio Conti has decided to retire from the Board effective at the Annual Meeting. Following Mr. Conti’s retirement, the Board expects to reduce the size of the Board to 12. Due to Mr. Conti’s retirement, there are fewer director nominees named in the proxy statement than the number fixed pursuant to the Company’s Articles. Proxies cannot be voted for a greater number of persons than the number of nominees named.

Our governing documents provide that a director nominee be elected by a majority of votes cast in an uncontested election. If an incumbent director nominee fails to receive a majority of the votes cast in an election that is not a contested election, the director must offer to tender a resignation, and the Board shall decide, through a process managed by the Governance/Nominating Committee, whether to accept or reject the resignation or whether other action shall be taken. In reaching its decision, the Governance/Nominating Committee and the Board may consider any factors they deem appropriate and relevant. The Board will act on the recommendation of the Governance/Nominating Committee at its next regularly scheduled meeting and will promptly disclose the rationale for its decision in a Form 8-K furnished to the SEC.

A shareholder may: (i) vote for the election of a nominee; (ii) vote against the election of a nominee; or (iii) abstain from voting on a nominee. Unless an executed proxy contains instructions to the contrary, it is assumed that the proxy will be voted “FOR” the re-election of each nominee named on the following pages.

The form of shareholder resolution for this proposal is below:

Aon values a number of attributes and criteria when identifying nominees to serve as a director, including professional background, expertise, reputation for integrity, business, financial and management experience, leadership capabilities, international experience and perspectives, and diversity of viewpoints, backgrounds, work and other experiences and other demographics, as well as the ability to commit sufficient time and attention to the activities of the Board. We believe all of the nominees are individuals with a reputation for integrity, demonstrate strong leadership capabilities, and are able to work collaboratively to make contributions to the Board and management. Biographical information about the nominees and the experience, qualifications, attributes, and skills considered by our Governance/Nominating Committee and the Board in determining that the nominees should serve as a director appears below.

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Director Nominee Bios

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Corporate Governance

We are committed to effective corporate governance, which we believe helps us sustain our success and build long-term value for our shareholders and other stakeholders. Aon’s Corporate Governance Guidelines provide the framework for our system of corporate governance, which, together with our committee charters and Code of Business Conduct, set forth standards of conduct for employees, officers and directors. The Board and its committees provide oversight of Aon’s overall performance, strategic direction, and executive management team performance, including management of the Company’s top risks and mitigation plans. The Board also reviews major initiatives and transactions and advises on key financial and business matters. The charter of each standing committee and sub-committee, the Corporate Governance Guidelines, and the Code of Business Conduct are available on the corporate governance section of our website at http://www.aon.com/about-aon/corporate-governance/corporate-governance.jsp. For more information about our Board’s and management’s oversight of risks please see “Board Role in Risk Oversight” below.

Board Leadership Structure

The positions of Chief Executive Officer and Chair of the Board are currently held by separate individuals. Greg Case serves as our Chief Executive Officer, and Lester Knight serves as the Non-Executive Chair of the Board. Pursuant to our Corporate

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Governance Guidelines, the same or different persons may hold the positions of Board Chair and Chief Executive Officer. At this time, the Board believes that having an independent Board Chair is the most appropriate Board leadership structure. As Non-Executive Chair, in addition to serving as liaison between the Board and management, Mr. Knight sets the agendas for, and presides over, the Board meetings and also chairs executive sessions of the non-management directors. Our Chief Executive Officer is also a member of the Board and participates in its meetings to provide valuable insight into the most significant developments facing the Company and to guide the Board’s discussion and review of the Company’s strategy. The Board believes the separation of the positions of Chief Executive Officer and Chair is the most appropriate structure at this time to best serve the Company and its shareholders, as it allows our Chief Executive Officer focus on the management of the Company and the Chair to ensure that the Board is focused on its oversight responsibilities, including independent oversight of management. The structure also facilitates robust communications between management and the Board and provides effective oversight by independent directors, including oversight of risks. The Board retains the flexibility to revise this structure based upon its periodic assessment and review of the Company’s needs and leadership.

Board Role in Risk Oversight

Risk is inherent and evolving in every business, and how well a business manages risk can ultimately determine its success. Our enterprise risk management (“ERM”) program covers the range of material risks to Aon, including strategic, operational, financial, compliance, human capital, technology, security and ESG risks. The Board oversees Aon’s risk management program and allocates certain oversight responsibilities to its committees or any sub-committee, as appropriate. Each committee regularly reports to the Board on risk matters under its purview. The Board and its committees regularly review our risk management policies, processes and controls. The Board has delegated to the Audit Committee the primary responsibility for the oversight of the Company’s ERM program.

Management carries out the daily processes, controls, and practices of our risk management program, many of which are embedded in our operations. In addition, as part of our ERM process, management identifies, assesses, prioritizes, monitors, and develops mitigation plans for Aon’s top risks. The Board believes that establishing the right tone at the top and maintaining full and open communication between management and the Board are essential for effective risk management and oversight. As such, the Board and its committees regularly review and discuss with management the Company’s risk landscape, ERM governance, and progress on key risk management priorities, including emerging risks associated with growth initiatives and changing geopolitical and macroeconomic conditions. Throughout the year, the Board and the committees review the Company’s management of risk, including but not limited to the areas of cybersecurity and data security, data privacy, business continuity, compliance with government regulations, errors & omissions claims, financial performance, liquidity, taxes, mergers and acquisitions, ESG and human capital management.

In addition, members of senior management attend Board and committee meetings (including private sessions with independent directors when invited) and are available to address any questions or concerns raised by the Board related to risk management and any other matters. For more information on committee responsibilities with respect to risk oversight, please see the section titled “Board of Directors and Committees” below.

Cybersecurity, Data Security, and Data Privacy Risk Management and Board Oversight

Cybersecurity, data security, and data privacy matters are an important focus of our Board’s oversight of risk. The Audit Committee has primary responsibility for the oversight of cybersecurity risk and engages in regular discussion with management regarding cybersecurity and privacy risk mitigation and incident management, including risks arising from the use of AI. The Company’s management, including the Chief Privacy and Data Trust Officer and the Chief Information Security Officer, regularly presents (no less than twice annually) to the Audit Committee of the Board regarding cybersecurity, data security, and data privacy matters.

Aon’s cybersecurity, data security, and data privacy programs are designed to protect the personal and confidential data of our clients and our colleagues. Aon engages in a risk-based approach to adopting and implementing appropriate technical, organizational, administrative, and physical safeguards for cybersecurity. One key component to safeguard against risks facing Aon’s technology and security is Aon’s ERM program, as discussed above, which includes management’s

2025 Aon Proxy Statement  17

identification, assessment, prioritization, and mitigation of cybersecurity risks. In addition, the Company has embedded responsible AI principles in its Code of Conduct and established a cross-functional AI working group which is focused on enabling innovation while mitigating risks. Our AI governance program assesses and prioritizes AI opportunities, solutions and risks across the firm, and the Company’s management provides relevant updates regarding such matters to the Board. In addition, employees across the Company receive periodic training and education on cybersecurity-related topics and governance matters.

Aon has established a Global Privacy and Data Trust Office led by a Chief Privacy and Data Trust Officer and comprised of full-time privacy professionals located around the globe, responsible for implementing Aon’s data privacy program, and designing and developing data privacy compliance solutions.

In addition, Aon maintains a global Information Security organization, led by our Chief Information Security Officer, with dedicated information security personnel responsible for protecting Aon’s information. Refer to Part I, Item 1C of Aon’s Annual Report on Form 10-K for the year ended December 31, 2024, for further information regarding Aon’s cybersecurity and risk management.

Oversight of Corporate Sustainability and ESG-related Risks and Opportunities

Our Board and management recognize that the full spectrum of corporate sustainability, including the priorities of ESG and related risks, are evolving in their significance to the business, and accordingly, oversight of ESG risks is a continuing and dynamic commitment. Aon’s Corporate Governance Guidelines provide that the full Board oversees the Company’s ESG risks and opportunities, as well as the Company’s ESG strategies, goals and objectives, and performance. The Board may from time-to-time delegate certain aspects of its ESG and related risk oversight responsibilities to one or more of its committees or sub-committees which report on such matters directly to the Board. The governance and ongoing execution of our ESG strategy is the responsibility of leaders and key internal partners across Aon, and the Board regularly reviews and oversees our ESG strategy, program and goals.

The Board reviews Aon’s ESG and climate strategy and, more generally, the Board (including through its committees) oversees the company’s ESG risks and opportunities, including human capital management, governance, climate, executive compensation, and inclusion and wellbeing. The full Board (or its committees) regularly reviews and discusses people-related risks and opportunities, including colleague satisfaction and engagement survey results, pay equity, colleague wellbeing, succession planning, employment law matters and conduct and ethics matters. The full Board also reviews progress against Aon’s inclusion and wellbeing strategy and initiatives. For more information on Aon’s approach to corporate sustainability and ESG efforts, please see our latest Aon Impact Report, which can be found on the Company’s website, www.aon.com. The information in the Aon Impact Report or otherwise on the Company’s website is not incorporated by reference into, and does not form part of, this proxy statement.

Director Independence

Aon’s Corporate Governance Guidelines require that a majority of directors meet the independence requirements of the New York Stock Exchange (the “NYSE”). The Corporate Governance Guidelines further provide that each of the Audit Committee, Governance/Nominating Committee and Compensation Committee be composed entirely of independent directors.

The Board has affirmatively determined that each nominee for director other than Mr. Case is independent. Mr. Case is considered a management director because of his position as our President and Chief Executive Officer. In addition, the Board has affirmatively determined that Dr. Carolyn Woo, who retired as a director effective as of June 21, 2024, was independent during the time she served on the Board, and that Mr. Conti, who will be retiring from the Board effective as of the Annual Meeting, is independent.

In determining that each of the non-management directors is independent, the Board also considered the following relationships that it deemed were immaterial to such director’s independence:

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Board of Directors and Committees

The Board met five times in 2024. All nominees for director who served as a director in 2024 attended at least 75% of the total meetings of the Board and the standing committees and sub-committees on which they served during the period for which they served. In accordance with NYSE rules and the Corporate Governance Guidelines, non-management directors meet regularly in executive session without management. Mr. Knight, the Non-Executive Chair, chairs these executive sessions.

The Board has five standing committees: the Executive Committee, the Audit Committee, the Finance Committee, the Governance/Nominating Committee and the Compensation Committee. The Board has also established the Inclusion & Wellbeing Sub-Committee as a standing sub-committee of the Governance/Nominating Committee.

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Other Corporate Governance Practices

Board and Committee Evaluations

Our Board engages in ongoing self-evaluation and assessment. Annually, the directors review and complete evaluations on Board effectiveness, committee performance and peer assessment. The Governance/Nominating Committee oversees the annual evaluation process and the Board retains an outside party to review the completed evaluations. Each of the committees and the full Board discuss their self-assessments in executive sessions at least annually. The Governance/Nominating Committee periodically reviews the form and process for Board and Committee self-evaluations. Feedback received regarding individual directors is shared with the Governance/Nominating Committee Chair and the individual directors. In addition, throughout the year, directors have regular opportunities to provide input directly to the Chairman, committee chairs and management on meeting process enhancements, resources, agenda topics for Board and committee meetings and strategy discussions. The Board believes that this evaluation process supports its effectiveness and continuous improvement, as well as continued focus on Board refreshment and composition.

Director Commitments

The Governance/Nominating Committee considers each director’s or nominee’s time commitments, including those related to employment and other board service, to assess the director’s or nominee’s capacity to meet their responsibilities. Our Corporate Governance Guidelines provide that a director must notify the Board Chair prior to accepting any invitation to serve on another public company board, and that a director may not serve on the boards of more than three other public companies, in addition to his or her service on the Board of the Company, unless otherwise approved by the Governance/Nominating Committee. In addition, directors must offer to resign from the Board as a result of a substantial change to their principal occupation, subject to further consideration by the Governance/Nominating Committee.

Director Onboarding and Education

Upon joining our Board, new directors are provided with a comprehensive onboarding covering key topics including our business, strategy and governance. New directors typically participate in introductory meetings with our senior business and functional leaders. On an ongoing basis, directors receive presentations on a variety of topics related to their work on the Board and within the industry, both from senior management and from experts outside of our Company. The Board also receives periodic briefings and education on core concepts and trends that impact our businesses such as information security and AI, and potential risks and opportunities. Directors may also enroll in continuing education programs sponsored by third parties at our expense.

CEO and Senior Leadership Succession Planning

Our Independent Board Chair oversees the Chief Executive Officer succession planning process. The full Board as well as the independent directors, at least annually, discuss CEO succession planning, including emergency succession plans and processes. The Board also regularly reviews and discusses senior leadership succession planning and development. Our Board reviews potential internal senior management candidates with our CEO and our Chief Administrative Officer, including the qualifications, experience, and development priorities for these individuals. Directors engage with potential CEO and senior management successors at Board and committee meetings and in less formal settings to allow directors to personally assess potential CEO and key executive successors. Further, our Board periodically reviews the overall composition of our senior management’s qualifications, tenure, and experience.

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Director Selection and Shareholder Recommendations

Consistent with our Corporate Governance Guidelines, the Governance/Nominating Committee seeks members from diverse backgrounds who combine a broad spectrum of experience and expertise with a reputation for integrity. The Governance/Nominating Committee also considers whether a potential nominee would satisfy independence standards adopted by the Board and the requirements of the NYSE. The Governance/Nominating Committee has sole authority to retain third-party search firms to identify director candidates and to approve such search firm’s fees and other retention terms.

In selecting nominees for director, the Governance/Nominating Committee considers professional background, reputation for integrity, leadership capabilities, skills and experience in the context of the needs of the Board, diversity, and international experience and perspectives. For more information regarding our directors, see page 5 of this proxy statement. When evaluating candidates for nomination as new directors, the Governance/Nominating Committee considers, and requests that the search firms it engages provide, a set of qualified candidates that includes individuals from diverse backgrounds with a variety of experiences and potential contributions to the Board.

When a vacancy exists on the Board due to the expansion of the size of the Board or the resignation or retirement of an existing director or as part of considering ongoing board succession planning, the Governance/Nominating Committee identifies and evaluates potential director nominees. The Governance/Nominating Committee recommends potential director candidates to the full Board, which is responsible for final approval of any director candidate. The effectiveness of the nomination process, including the criteria used for selecting nominees for director, is evaluated by the Board each year as part of its annual self-evaluation process and by the Governance/Nominating Committee as it evaluates and identifies director candidates. Our newest director, Admiral Stavridis, (who was appointed to the Board in August 2024) will stand for election at the Annual Meeting. Admiral Stavridis was identified as a director candidate by a member of the Company’s management for consideration by the Governance/Nominating Committee.

The Governance/Nominating Committee will consider shareholder recommendations for director nominees. Shareholder recommendations will be evaluated against the same criteria used to evaluate other director nominees, which are discussed under “Proposal 1 – Resolutions Regarding the Election of Directors” on page 9 of this proxy statement. Recommendations, together with the name and address of the shareholder making the recommendation, relevant biographical information regarding the proposed nominee and a description of any arrangement or understanding between the shareholder and the proposed nominee, together with any other information required by the Articles, should be sent to the Company Secretary. Shareholder recommendations for director candidates to stand for election at the 2026 annual general meeting must be submitted in writing to the Company Secretary, Aon plc, 15 George’s Quay, Dublin 2, Ireland. Recommendations will be forwarded to the Chair of the Governance/Nominating Committee for review and consideration. For information regarding compliance with the requirements applicable to shareholder nominations to the Board, see “Shareholder Proposals for 2026 Annual General Meeting” on page 94 of this proxy statement.

Communications with the Board of Directors

Shareholders and other interested parties may communicate with the Board, any committee of the Board, our independent Chair, or any of our directors by contacting the non-management directors of Aon plc, c/o the Company Secretary, 15 George’s Quay, Dublin 2, Ireland, or by sending an email to corporate.governance@aon.com.

The non-management directors have established procedures for handling communications from shareholders and other interested parties. Communications are distributed to the Chair of the Governance/Nominating Committee, the full Board, the non-management directors, or to any individual director or directors as appropriate, depending on the facts and circumstances outlined in the communication. The Company Secretary will not distribute communications that are unrelated to the duties of the Board, such as spam, junk mail, mass mailings, business solicitations, and advertisements.

Shareholder Engagement

It has been our long-standing practice to actively engage with our shareholders throughout the year so that management and the Board can better understand shareholder perspectives on long-term strategy, governance, executive compensation, human capital management and other topics.

Following our 2024 Annual Meeting, we reached out to our largest shareholders representing over 50% of our outstanding shares, to discuss our say-on-pay vote and other matters of interest to them, including our results and strategy, long-term expectations and financial guidance, corporate governance structure, Board composition and director refreshment and

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tenure, Board oversight of risks, succession planning, executive compensation, including performance-based executive awards, and corporate sustainability related matters. Shareholders representing approximately 42% of our outstanding shares responded to our meeting invitation and met with members of our senior management team, and, in some instances, an independent Board member. We also met with shareholders who proactively requested to meet.

During these meetings, we specifically sought input from shareholders regarding our 2024 say-on-pay vote and enhancements we could make to improve our disclosures regarding our executive compensation programs. In these meetings, several shareholders provided feedback with respect to the structure and quantum of the special awards granted to our then-serving CFO and our then-serving President in 2023, and suggested opportunities to enhance our compensation-related disclosure. We also took the opportunity during these meetings to provide our shareholders with an overview of the Company’s plans to respond to the 2024 say-on-pay vote, and to review shareholder feedback with the Compensation Committee and the full Board for their assessment.

In addition, throughout the year we engage in extensive investor relations, in which members of management regularly meet with investors to discuss Company strategies, financial and operating performance, capital allocation priorities and other topics of interest. In 2024 these outreach activities included engagement of an external firm to conduct an investor perception study involving discussions with large investors to help inform areas of focus and topics of importance to investors.

We share shareholder feedback from these discussions with our Board and its committees, including the Compensation Committee, as we seek to enhance our corporate governance, sustainability and executive compensation practices and improve our disclosures.

2024 Shareholder Engagement Highlights

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Giving consideration to the feedback we received from investors during our 2024 and 2023 engagement meetings, our Board approved enhancements to our Corporate Governance Guidelines to formalize Board oversight of corporate sustainability and ESG activities and director time commitments. We also continued our approach to director refreshment by electing two new directors in 2024 and adding newer directors to two Board committees. In addition, we expanded disclosure of our CEO and senior management succession planning process.

For more information on our shareholder engagement efforts with respect to executive compensation and consideration of last year’s say-on-pay vote and how we are responding, see page 33 of the Compensation Discussion and Analysis in this proxy statement.

Majority Voting

The Articles and our Corporate Governance Guidelines require that directors be elected by a majority of votes cast in an uncontested election. In a contested election, directors will be elected by plurality vote. In addition, the Corporate Governance Guidelines provide that any incumbent director who fails to receive a majority of the votes cast in an election that is not a contested election, must immediately tender his or her resignation to the Board. The Board will then determine, through a process managed by the Governance/Nominating Committee, whether to accept or reject the resignation, or whether other action shall be taken. In reaching its decision, the Governance/Nominating Committee and the Board may consider any factors they deem appropriate and relevant. The Board will act on the recommendation of the Governance/Nominating Committee at its next regularly scheduled meeting and will promptly disclose the rationale for its decision in a Form 8-K furnished to the SEC.

Share Ownership Guidelines

The Board has adopted Share Ownership Guidelines for Non-Management Directors and Officer Share Ownership Guidelines to align the interests of directors and executive officers with the interests of our shareholders. The guidelines specify a dollar value (expressed as a multiple of salary or cash retainer) of shares that executive officers and directors are expected to accumulate and hold while serving in these positions. The Share Ownership Guidelines for Non-Management Directors provide that each non-management director should attain an investment position in Class A Ordinary Shares equal to five times the annual director retainer. The Share Ownership Guidelines for Non-Management Directors also establish retention rules generally requiring that all shares received by a director (net of withholding, if any) pursuant to his or her service as a Board member be retained until the required investment position is attained. Compliance with the Share Ownership Guidelines for Non-Management Directors is reviewed by the Board on an annual basis, and each non-management director was in compliance for 2024.

Class A Ordinary Shares counted toward attainment of the Share Ownership Guidelines for Non-Management Directors include shares owned outright and shares owned through trusts or entities controlled by the non-management director.

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Security Ownership of Directors and Executive Officers

The following table sets forth the number of Class A Ordinary Shares beneficially owned as of April 11, 2025 by each of Aon’s directors, nominees and NEOs and by Aon’s directors and executive officers as a group. As used in this proxy statement, “beneficially owned” means a person has, or may have within 60 days, the sole or shared power to vote or direct the voting of a security and/or sole or shared investment power with respect to a security (i.e., the power to dispose or direct the disposition of a security). No shares held by Aon’s directors or executive officers are pledged as security. The address of each person named in the table below is c/o Aon plc, 15 George’s Quay, Dublin 2, Ireland.

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Principal Holders of Voting Securities

As of April 11, 2025, the beneficial owners of 5% or more of Aon’s Class A Ordinary Shares entitled to vote at the Annual Meeting and known to the Company were:

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Proposal 2–Advisory Resolution on Executive Compensation

What am I voting on?

In accordance with applicable law and Section 14A of the Exchange Act, we are providing shareholders with the opportunity to vote on an advisory resolution, commonly known as “say on pay,” approving Aon’s executive compensation as reported in this proxy statement. At our 2024 annual general meeting, we provided shareholders with the opportunity to vote on an advisory resolution regarding the executive compensation of our NEOs as disclosed in the proxy statement for the 2024 annual general meeting, and shareholders approved the proposal by a vote of approximately 69% of the votes cast “for”. Following the results of the “say on frequency” vote held in 2023, we currently conduct advisory “say-on-pay” votes on an annual basis, and we expect to conduct our next advisory vote at our 2026 annual general meeting of shareholders.

We encourage shareholders to read the Compensation Discussion and Analysis beginning on page 31 of this proxy statement, which describes in detail how our compensation policies and procedures operate and are designed to achieve our compensation objectives of (1) directly linking the compensation of our NEOs to our performance and (2) aligning the financial interests of our NEOs with those of our shareholders. We further encourage our shareholders to refer to the Summary Compensation Table for Fiscal Years 2024, 2023, and 2022, and other related tabular and narrative disclosures beginning on page 49 of this proxy statement, which provide detailed information on the compensation of our NEOs.

The Board and the Compensation Committee believe that the policies and procedures articulated in the Compensation Discussion and Analysis are effective in achieving our executive compensation objectives and that the design of our compensation program and the compensation awarded to our NEOs fulfill these objectives.

The form of shareholder resolution for this proposal is below.

RESOLVED THAT, the shareholders approve, on an advisory basis, the compensation of the Company’s named executive officers as described in the proxy statement for the 2025 Annual General Meeting of the Company under “Compensation Discussion and Analysis” and “Executive Compensation,” including the tabular and narrative disclosure contained in the proxy statement.

Is this vote binding on the Board?

As this vote is advisory, it will not be binding upon the Board or the Compensation Committee, and neither the Board nor the Compensation Committee will be required to take any action (or refrain from taking any action) as a result of the outcome of the vote on this proposal. The Compensation Committee will review and consider the outcome of the vote in connection with the ongoing review of Aon’s executive compensation programs.

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Compensation Discussion and Analysis

This Compensation Discussion and Analysis (“CD&A”) describes our executive compensation program for our Named Executive Officers (each an “NEO” and collectively the “NEOs”), who are listed below, for 2024. We recommend that you read this section in conjunction with the executive compensation tables and corresponding footnotes that follow, as it provides context for the amounts shown in the tables and the footnote disclosures.

Executive Summary

Who We Are

Aon exists to shape decisions for the better — to protect and enrich the lives of people around the world. Through actionable analytic insight, globally integrated Risk Capital and Human Capital expertise, and locally relevant solutions, our colleagues provide clients in over 120 countries with the clarity and confidence to make better risk and people decisions that protect and grow their businesses.

2024 Business Highlights

In assessing our performance, we focus on four non-GAAP metrics that we communicate to shareholders: organic revenue growth, adjusted operating margin, adjusted diluted earnings per share, and free cash flow. Management believes that these measures are important to make meaningful period-to-period comparisons and that this supplemental information is helpful to investors. Management also uses these measures to assess our operating performance and performance for purposes of our compensation program. These non-GAAP metrics should be viewed in addition to, not instead of, our consolidated financial statements and notes thereto. A reconciliation of these non-GAAP metrics to the most directly comparable GAAP metrics is set forth in Appendix A to this proxy statement.

In 2024, we delivered strong performance across each of these four metrics:

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Performing at the levels described above allows us to continue to execute our capital allocation model, which balances high-return investments in growth and capital return to shareholders.

During 2024, we completed the acquisition of NFP, meaningfully expanding our presence in the fast-growing middle market segment. We also returned $1.6 billion of capital to shareholders through share repurchases and dividends, highlighting our strong free cash flow generation and effective allocation of capital. Our consistent focus on the four key financial metrics described above and our disciplined approach to capital allocation has helped drive meaningful total shareholder returns throughout the tenure of our senior management team. Specifically, during Mr. Case’s leadership, which began in April 2005, our average annual total shareholder return has been approximately 16%, compared to the return of the benchmark Standard & Poor’s (the “S&P”) 500 of approximately 8% and approximately 13% for our industry peer averages (Arthur J. Gallagher & Co., Brown & Brown, Inc., Marsh & McLennan Companies, Inc., and Willis Towers Watson plc). We believe we are well positioned to drive long-term value creation by delivering sustainable organic revenue growth, consistent earnings growth, and strong free cash flow generation.

We compensate our senior executives through incentive plans that measure both long-term and short-term performance. Our regular long-term incentive plan (described in this CD&A under “Long-Term Leadership Performance Program Under Our Shareholder-Approved Plan” or “LPP”) is based on cumulative adjusted diluted earnings per share, a measure driven by operational performance and capital management, across overlapping three-year performance periods. Our short-term incentive plan (described in this CD&A under “Annual Incentive Awards Under Our Shareholder-Approved Plan”) is primarily based on adjusted operating income, a measure driven by operating margin and organic revenue growth, as well as a people and culture component, which assesses the Company’s progress against pre-defined workplace objectives.

We achieved strong results across these metrics, which were the key performance measures under our 2022-2024 long-term and 2024 annual incentive compensation plans. Set forth below are the results across these metrics as well as the results against their GAAP comparative metrics:

In addition, the Company has progressed our People and Culture goals, as measured by our annual colleague survey, including improvement of colleague wellbeing, inclusive work environment, and strong colleague engagement results, while also maintaining strong colleague retention.

2024-2025 Leadership Transitions

In April 2024, Christa Davies notified the Company of her intention to retire from the position of Executive Vice President and Chief Financial Officer. Ms. Davies served as Chief Financial Officer until July 29, 2024, and is serving as a senior advisor through May 31, 2026. A discussion of Ms. Davies’s transition agreement appears on page 53.

In July 2024, Edmund Reese was appointed Executive Vice President and Chief Financial Officer. When determining Mr. Reese’s annual base salary and target annual incentive award, the Compensation Committee reviewed market data provided by its independent compensation consultant, Meridian Compensation Partners, LLC (“Meridian”), as well as Mr. Reese’s compensation from his prior employer. Because of certain compensation that Mr. Reese forfeited in connection with his prior employment and to induce him to accept employment with the Company, Mr. Reese’s annual incentive award for 2024 was guaranteed to be paid at target (200% of base salary), without proration, and Mr. Reese received a sign-on grant of performance share units and restricted share units and a cash sign-on bonus, the terms of which are described below. Mr. Reese also received an annual LPP award in the form of PSUs consistent with the grants made to the other NEOs. A discussion of Mr. Reese’s employment letter appears on page 52.

In March 2025, Mr. Andersen transitioned from the role of President to the role of senior advisor for the remainder of the employment term (June 30, 2026) pursuant to Section 5(a) of his employment agreement. A discussion of Mr. Andersen’s employment agreement appears on page 54.

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2024 Say-on-Pay Result & Actions Taken in Response to Shareholder Feedback on Executive Compensation

We value the views of our shareholders and engage with them regularly throughout the year, as described earlier under the section titled Shareholder Engagement. The feedback received from our shareholder engagement efforts provides important inputs into decisions surrounding our corporate governance and executive compensation programs. Generally, we engage with our investors year-round through active outreach and responsiveness to inbound requests. In addition to formal engagement meetings, we occasionally solicit general perceptions about our Company through third-party administered investor surveys, as was done in the Fall of 2024.

Following a lower than desired advisory Say-on-Pay proposal approval of 68.8% at our 2024 Annual Meeting, we actively solicited input on our executive compensation program and related disclosures from shareholders. Specifically, starting in August 2024, and continuing throughout the Fall, we reached out to our largest institutional shareholders, representing over 50% of our outstanding shares, and shareholders representing approximately 42% of our outstanding shares responded to our meeting invitation and met with senior colleagues from Investor Relations, Legal, and Human Resources and in appropriate instances with an independent director.

We focused these efforts on listening to our shareholders to better understand their perspectives on our executive compensation program, including the concerns of those who voted against last year’s Say-on-Pay proposal, to ensure our approach to executive compensation aligns with the expectations of our shareholders and regain the support of those that voted against. Overall, investors expressed their understanding and support for our regular compensation program and structure and its alignment with our Pay-for-Performance philosophy. All feedback received was shared and discussed with the Compensation Committee and the full Board.

Shareholders provided a variety of general feedback and suggestions regarding certain incentive metrics and disclosures regarding Board oversight and succession. However, we received specific input on two key areas that contributed to a lower Say-on-Pay vote result in 2024: 1) special one-time awards made to two NEOs in FY 2023; and 2) transparency in the pay-setting process. This input, along with a range of perspectives and suggestions received during our shareholder engagement, informed the Compensation Committee’s decision to provide more clarity surrounding the Company’s limited use of one-time awards as part of our ongoing executive compensation program and to provide enhanced transparency into the regular decision-making process surrounding incentives, as summarized below.

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We remain committed to ongoing engagement with our shareholders to ensure our executive compensation program continues to align with their expectations and our long-term business strategy.

Features of Our Executive Compensation Program

The following table provides an overview of our compensation program elements for our NEOs. The guiding philosophy underlying our executive compensation program is to provide a fair, flexible, and market-based total compensation package with a significant portion of actual compensation paid or provided meaningfully tied to the Company’s short- and long-term performance and aligned with the interests of our shareholders.

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Our Pay for Performance Orientation and Executive Compensation Philosophy

The core principle of our executive compensation program continues to be pay for performance, as we progress toward our goal of being the leading global professional services firm focused on delivering human capital and risk capital solutions to our clients. That core principle dictates that performance-based pay elements (which constitute a significant portion of our NEOs’ total direct compensation (consisting of base salary, annual incentive compensation granted for 2024 performance and long-term incentive compensation granted in 2024 for the 2024-2026 performance period)) will not be earned or paid unless specified performance objectives are achieved. For 2024, performance-based compensation comprised approximately 94% of the total direct compensation for Mr. Case and averaged approximately 84% of the total direct compensation for our other NEOs:

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The “Performance-Based” pay component shown in the above graphs is the sum of (1) the cash portion of the NEO’s bonus paid for 2024 performance, plus (2) the grant date fair value of equity awards granted to our NEOs during 2024 (with long-term equity awards based on grant date value assuming target performance), and excludes Ms. Davies’s 2024 compensation (given that she retired from her CFO role in 2024). The “Fixed” pay component is the NEO’s 2024 base salary. For our NEOs other than Mr. Case and other than Ms. Davies, the actual performance-based percentage of total direct compensation ranged from 73% to 89%.

In addition to our focus on pay for performance, our executive compensation program is complemented by practices designed to mitigate compensation-related risk and align with the long-term interests of our shareholders:

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The Executive Compensation Process

Process of Determining Executive Compensation

Management assists the Compensation Committee in developing and administering our executive compensation program. Direct responsibilities of management include, but are not limited to:

In the first quarter of 2024, our independent Board members evaluated our Chief Executive Officer’s performance and compensation. At that time, the Compensation Committee also evaluated the performance and reviewed the compensation of our other executive officers. During this review, the Compensation Committee approved each executive officer’s annual base salary and target annual incentive for 2024 performance, and the specific corporate performance metrics against which our performance would be measured for purposes of this annual incentive award. The Compensation Committee also approved in March 2024 a target number of PSUs to be awarded to each executive officer under the LPP.

In early 2025, in connection with the Compensation Committee’s annual compensation review, management presented the Compensation Committee with compensation tally sheets reporting compensation paid for the prior four years and competitive pay data. The Compensation Committee also reviewed and considered Aon’s overall performance against targets that were established for 2024. This review culminated in certain compensation decisions made by the Compensation Committee with respect to our executive officers during the first quarter of 2025, which are described in more detail below.

Engagement of Independent Compensation Consultant

The Compensation Committee retains Meridian Compensation Partners, LLC (“Meridian”) as its independent compensation consultant. Meridian is engaged by, and reports directly to, the Compensation Committee, and advises on matters covered by the Compensation Committee’s Board-approved charter, while doing no work for management. Meridian typically participates in all Compensation Committee meetings and communicates with the Chair of the Compensation Committee and management between meetings. During 2024, Meridian assisted the Compensation Committee by: advising on our compensation philosophy, objectives, and strategy; reviewing the competitiveness and effectiveness of our senior executive and Board compensation levels and program structure; advising on compensation levels for newly hired executives; identifying our peer group for executive and Board compensation and Company performance review purposes; assessing

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potential compensation-related risks; providing change-in-control severance calculations for our NEOs in the 2024 annual proxy disclosure; providing compensation data from our peer group based on their proxy statements and other disclosures; reporting on executive-compensation related trends, say-on-pay governance, and regulatory initiatives; and reviewing and commenting on related disclosures. Management periodically retains other consulting firms to provide pay survey data and other non-executive compensation services.

The Compensation Committee has assessed the independence of Meridian pursuant to the SEC and NYSE rules and concluded that no conflict of interest exists that would prevent Meridian from serving as an independent consultant to the Compensation Committee.

How We Determine Compensation

The Compensation Committee generally targets a competitive level and mix of total direct compensation elements using market data as a reference point. For 2024, the Compensation Committee did not use a specific formula or comparative percentile targets to determine total compensation, individual components of compensation, or the relative mix of pay components, and the establishment of compensation levels in 2024 was not a mechanical process. Rather, the Compensation Committee used its judgment and business experience. The Compensation Committee’s overall intent was to evaluate the various elements of total compensation so that the emphasis of the Company’s executive compensation program was on its variable components of pay in the form of long-term equity and annual bonus award opportunities, and the amounts earned from such awards, which vary based on Aon’s performance.

Use of Tally Sheets

The Compensation Committee regularly reviews compensation tally sheets. The tally sheets assign dollar amounts to each component of the executives’ compensation, including base salary, annual incentives (target and actual), long-term incentives granted and outstanding, employee benefits (including health care and qualified and nonqualified retirement plans), relocation benefits, including income tax equalization, perquisites, and potential change in control severance payments. The tally sheets are presented to the Compensation Committee to help ensure that it is aware of all rewards components and the value of such components when making compensation decisions.

Involvement of Mr. Case in the Compensation Process

Each year, the Compensation Committee approves all elements of compensation for our NEOs and other executive officers other than Mr. Case, whose compensation is approved by the independent directors of the Board. These decisions are typically made during the annual compensation review process conducted in the first quarter of the year. The Compensation Committee solicits certain recommendations from Mr. Case and our Chief Administrative Officer.

Mr. Case recommends to the Compensation Committee the regular annual long-term equity awards, annual incentive payments, base salary adjustments, and other one-time awards, if any, for the executive officers who report directly to him. He has direct knowledge of the contributions made to Aon by these executive officers, and he shares this knowledge with the Compensation Committee and provides feedback on the performance of his direct reports.

During the annual review process, our Chief Administrative Officer and the Chair of the Compensation Committee work together on Mr. Case’s annual evaluation report, which summarizes Mr. Case’s qualitative and quantitative performance for the year. The report is considered, along with other factors (including the Compensation Committee’s own assessment of Mr. Case’s performance, relevant market data, and Aon’s overall performance), in recommending Mr. Case’s compensation to the independent directors of the Board.

The Compensation Committee has the ultimate authority to make compensation decisions for our NEOs and other executive officers except for Mr. Case. The Compensation Committee discusses its preliminary compensation decisions with independent members of the Board who do not serve on the Compensation Committee. As part of this process, these directors share their evaluations of the executives’ performance. The sharing of performance review information also aids the directors in carrying out their succession planning responsibilities. After considering input from those directors, the Compensation Committee makes its final compensation determinations.

Mr. Case, together with our Chief Administrative Officer and our Chief Financial Officer, makes recommendations to the Compensation Committee relating to the performance targets to be established under Aon’s annual incentive and long-term

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equity incentive plans. The Compensation Committee reviews such recommendations with its independent compensation consultant and reserves the ultimate authority to set such targets and to determine whether such targets were achieved.

Internal Pay Relationships

In determining an executive officer’s target annual incentive or long-term performance award value, the Compensation Committee will, from time to time, consider internal pay relationships. However, the Compensation Committee has not adopted a broad internal pay comparability policy pursuant to which each executive officer’s compensation, or one or more components thereof, is related to or benchmarked against the compensation of other executive officers.

Analysis of Key 2024 Compensation Decisions

Peer Group

The Compensation Committee selects our executive compensation peer group based on a process that considers objective criteria, including industry segment; revenues, market capitalization, assets, and employee headcount; business complexity; and global reach; as well as peers of our direct peers (“peers of peers”) and proxy-advisor compensation peer groups. The Compensation Committee’s goal is to have relevant market data to inform its decisions on pay levels and practices. As such, the Compensation Committee looks for peer-group balance with larger and smaller companies in a comparable range, and to have continuity through an annual review process.

Industry-related criteria used as guidelines for identifying peers include global financial services companies and major professional services firms that we compete with for executive talent and/or financial capital. Size-related criteria used as guidelines for identifying peers include companies that are one-fourth to four times our size in average market capitalization (calculated over the most recent eight quarters to reduce volatility) and in trailing four-quarter revenues, and that have latest year total assets less than $500 billion.

Our peer group members are reviewed on an annual basis with Meridian. In 2024, we reviewed our peer group and concluded that no changes should be made to the peer group for 2025. Our 2024 and 2025 peer group members are listed below.

Base Salary

Using the peer group and executive compensation review processes outlined above, the Compensation Committee annually considers and reviews base salaries for our executive officers. Base salaries are adjusted periodically to, among other things, recognize changes in job responsibilities or bring the fixed component of an executive’s total compensation in line with his or her peers at the Company or the industry generally. Base salary adjustments generally take effect on April 1. In 2024, the Compensation Committee, consistent with the recommendations of our Chief Executive Officer, determined that the base salary for Ms. Simon, our Chief Operating Officer, would be adjusted from $675,000 to $800,000, to recognize her demonstrated capability since joining the Company in 2022. In 2025, the Compensation Committee further adjusted Ms. Simon’s base salary to $900,000, to better position her total compensation against the peer group. No other NEOs received a base salary adjustment in 2024. Mr. Reese’s base salary was set at $1,000,000 at the time he commenced employment with the Company, as described above.

Annual Incentive Awards Under Our Shareholder-Approved Plan

Annual Incentives. Under our Shareholder-Approved Plan, the Compensation Committee annually approves the framework for our annual incentive compensation plan, including the applicable Aon-wide performance metric and minimum achievement

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threshold against that performance metric. If the threshold level performance metric is not achieved, then no annual incentives are payable under our Shareholder-Approved Plan. If the minimum achievement threshold is achieved, then our Shareholder-Approved Plan allows for the payment of current-year annual incentives to each of our executive officers up to a cap of the lesser of $10 million or the two times target maximum annual incentive otherwise established by the Compensation Committee for the applicable executive officer. Our Chief Executive Officer retains the discretion to approve increases (up to 10%, subject to Compensation Committee consent) and decreases (up to 20%, not subject to consent) in the size of the incentive pool. However, no individual may receive an award in excess of the maximum amount established by the Compensation Committee.

In the first quarter of 2024, the Compensation Committee set target 2024 annual incentive opportunities for our then-employed NEOs in the context of their total compensation opportunities considering the performance and growth of the NEOs in both capability and scope when reviewed against the competitive market. For each NEO, annual incentive opportunities were set as a target percentage of the executive’s base salary at end of the performance year (and, for Ms. Davies, including her annual foreign service allowance received in connection with her relocation to London). The target annual incentives for each of our NEOs for 2024 remained unchanged from 2023, and are shown in the table below:

As explained below, for 2024, the Compensation Committee used a framework (the “Senior Executive Incentive Compensation Plan” or “SEICP”) for determining actual annual incentives to be earned if the threshold level of achievement of the metric under our Shareholder-Approved Plan was achieved.

2024 Performance Metrics. In the first quarter of 2024, the Compensation Committee determined that 2024 Aon-wide performance would be measured by two components for purposes of annual incentive awards. First, 80% of the performance would be measured by the growth in our adjusted operating income (“OI”) for 2024 as compared to a 2023 baseline adjusted OI number of $4,223 million, with a hurdle representing a 200-bps increase in year-over-year adjusted OI. The Compensation Committee retained the discretion to further adjust OI for material or significant items. The Compensation Committee selected OI as the primary measure to emphasize performance of Aon as a whole and link executives’ awards to Aon’s key business initiatives.

Second, 20% of the performance would be measured by the Compensation Committee’s assessment of the Company’s progress against quantitative goals with respect to people and culture on a firm-wide basis, (the “People & Culture” component). This component is intended to be leveraged (0% to 200%), and success is measured by examining the number of pre-established goals met and the degree of over-or under-performance across the goals established by the Compensation Committee, as described below.

In addition, the Compensation Committee set a minimum achievement threshold at 70% of the 2023 adjusted OI, or $2,956 million. The Compensation Committee set the minimum threshold at 70% because it believed performance below that level would not create enough value for the Company’s shareholders and, therefore, should not result in annual incentive payments. If the minimum achievement threshold was satisfied, an annual incentive pool may be funded as described below under “Determining 2024 Annual Incentives.”

2024 Actual Performance. The Company’s adjusted OI for 2024 was $4,939 million for purposes of determining 2024 annual incentives, which exceeded the minimum achievement threshold of 70% of our 2023 adjusted OI established under our Shareholder-Approved Plan. The $4,939 million of 2024 adjusted OI was 17.0% greater than 2023 adjusted OI of

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$4,223 million, or 15.0% greater than our 200-bps hurdle, resulting in a performance factor of 115.0% for the financial component of the annual incentive program. The Compensation Committee reviewed the Company’s progress against a robust set of goals demonstrating progress in our People & Culture component of the annual incentive program. The Committee determined that the Company progressed on the majority of its objectives, as measured in part by our annual colleague survey, including improvement of colleague wellbeing, inclusive work environment, and colleague engagement results. The Company also maintained strong retention of our colleagues deemed to be high-potential. Based on its assessment of progress around these goals, the Compensation Committee determined that the overall performance factor was 125% of target for the People & Culture component.

Determining 2024 Annual Incentives. In accordance with our Shareholder-Approved Plan, the SEICP would not be funded for 2024 unless Aon achieved the minimum achievement threshold of 70% of the 2023 baseline OI. After determining that this minimum threshold had been achieved, the Compensation Committee met in February 2025 to determine the funding status of the SEICP pool for 2024. After application of the formula guidelines described above, the total incentive pool reserved for participating members of the Company’s senior management team (including our NEOs) was determined to be approximately $15.9 million, or 117% of target. In determining annual incentives for our NEOs, the Compensation Committee (or, with respect to Mr. Case, the independent members of the Board) considered Mr. Case’s compensation recommendations for the NEOs (other than himself), business and financial results, individual delivery of key strategic initiatives and personal leadership qualities. While each NEO demonstrated strong personal performance during 2024, the Compensation Committee (and, with respect to Mr. Case, the independent members of the Board) decided to not pay out the full incentive pool for 2024.

Mr. Case. The independent directors of the Board determined that, under Mr. Case’s leadership, the Company delivered continued strong progress across the four key financial metrics that we report to shareholders: organic revenue growth, adjusted operating margin, adjusted diluted earnings per share, and free cash flow (the “Four Key Financial Metrics”). Organic revenue growth was 6%, operating margin on an adjusted basis was 31.5%, adjusted diluted earnings per share increased 10% to $15.60, and free cash flow was $2.8 billion. During 2024, the firm returned $1.6 billion of capital to shareholders through share repurchases and dividends. Under Mr. Case’s leadership, Aon made significant progress on its 3x3 Plan to drive our Aon United strategy, bringing together Risk Capital and Human Capital, strengthening the Aon Client Leadership model, and accelerating service delivery and innovation through Aon Business Services. Mr. Case’s leadership was instrumental in progress made on key strategic initiatives to support the 3x3 Plan, including acceleration of our Aon Business Services strategy, optimization of our workforce, and accelerated the closing of the acquisition of leading middle-market broker, NFP. Mr. Case led execution of these initiatives while continuing to navigate a dynamic external economic environment, the ongoing competitive talent market, and other challenges to achieve continued record-high colleague engagement, high colleague retention rates and increased organic hiring in strategic focus areas. Mr. Case received an award of 100% of target for fiscal year 2024, based on the Company’s and his individual performance.

Mr. Reese. Mr. Reese’s employment as the Company’s Chief Financial Officer began on July 29, 2024. Mr. Reese contributed substantially to the Company’s strong business and financial results in 2024, including the Four Key Financial Metrics that we report to shareholders. His leadership in the transition of responsibilities from the Company’s former Chief Financial Officer and in overseeing the Company’s financial performance and capital allocation strategy, including M&A, financial reporting, and investor relations, among other areas, meaningfully contributed to the firm’s performance in 2024. Pursuant to his employment letter, Mr. Reese received a guaranteed award of 100% of annual target for fiscal year 2024.

Ms. Davies. The Compensation Committee determined that Ms. Davies’s individual efforts during her service as the Company’s Chief Financial Officer from January 1, 2024 to July 29, 2024 contributed substantially to the Company’s strong business and financial results in 2024, including the Four Key Financial Metrics that we report to shareholders. Her leadership in establishing the financial goals and implementing the 3x3 Plan meaningfully contributed to the firm’s approximately $700 million free cash flow and 33.8% adjusted operating margin for the first six months of 2024. Further, she led our disciplined approach to capital allocation, realizing the completion of $500 million in share repurchases during the first six months of 2024, and provided financial and operational leadership in preparation for our accelerated closing of the acquisition of NFP, including executing the Company’s financing strategy for the acquisition. The Compensation Committee noted that Ms. Davies transitioned from her role as Chief Financial Officer on July 29, 2024 and, pursuant to her transition agreement with the Company, Ms. Davies received a pro-rated amount equal to 100% of target for fiscal year 2024 for the portion of such year that she served as Chief Financial Officer, based on the Company’s and her individual performance.

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Mr. Andersen. The Compensation Committee determined that Mr. Andersen’s individual efforts contributed substantially to the Company’s strong business and financial results in 2024, including the Four Key Financial Metrics that we report to shareholders. Mr. Andersen’s leadership was essential to delivering consistently strong organic revenue growth across all solution lines, including 7% in each of Wealth Solutions and Reinsurance Solutions, as well as 6% in Health Solutions and 5% in Commercial Risk Solutions. Mr. Andersen led the firm’s Independent and Connected integration strategy with NFP to leverage the scale and capabilities of the firm while preserving the entrepreneurial culture and effective acquisition platform that has made NFP successful in the middle market. Mr. Andersen’s leadership was instrumental in supporting colleague engagement and retention in a competitive talent marketplace, and he continued to serve as a strong representative of the firm with clients and markets. Mr. Andersen received an award of 100% of target for fiscal year 2024, based on the Company’s and his individual performance.

Ms. Stevens. The Compensation Committee determined that Ms. Stevens’s individual efforts contributed substantially to the Company’s strong business and financial results, as well as the implementation of the 3x3 Plan, and to the attraction, retention, and motivation of leading talent. These and other actions have enabled the firm to achieve alignment across its leadership globally, to swiftly adopt and implement the 3x3 Plan, and to increase our record-high colleague engagement and continued strong colleague retention in a competitive talent market. Further, Ms. Stevens made significant contributions in strategic workforce planning, overseeing the management of succession planning, and managing hiring and attrition in line with business demand. Her contributions to our 3x3 Plan implementation and accelerating Aon United included her efforts in reshaping and redeploying colleagues for maximum impact and alignment with client demand and building longer-term infrastructure around skills-based hiring and development. Ms. Stevens was instrumental in supporting colleague development and retention in a competitive talent marketplace, and in setting a standard for impactful leadership within the firm. Ms. Stevens was promoted to Chief Administrative Officer during the year and added responsibilities for marketing, communications and public affairs to her existing responsibilities as the leader of our people organization. Ms. Stevens has begun to develop new strategies in each of these areas to continue to advance the firm and the 3x3 Plan. Ms. Stevens received an award of 107% of target for fiscal year 2024, based on the Company’s and her individual performance.

Ms. Simon. The Compensation Committee determined that Ms. Simon’s individual efforts contributed substantially to the Company’s strong business and financial results, as well as significant acceleration of service delivery and innovation capabilities through Aon Business Services. Ms. Simon has developed a strategy for leveraging data, analytics, technology and process to develop, deploy and continuously iterate enhanced capabilities for serving clients. During 2024, the firm released award-winning applications to better serve clients and make colleagues and clients more efficient and effective. These advancements are adding new insights and enabling a distinctive colleague and client experience that is helping us win more clients, do more with them and retain them longer, and is also contributing to improvements in colleague engagement, retention and hiring. Ms. Simon also advanced the firm’s AI strategy, enabling colleagues to leverage our considerable data to better serve current and emerging client needs. Ms. Simon received an award of 106% of target for fiscal year 2024, based on the Company’s and her individual performance.

For 2024, earned annual incentives for our NEOs were paid in a combination of cash (65%) and RSUs (35%) that further vest over a three-year period, except for (i) our Chief Executive Officer, who received a combination of cash (65%) and PSUs (35%) that vest over a three-year period and (ii) Ms. Davies, our former Chief Financial Officer, who received full payment in cash pursuant to her employment transition agreement. The following table sets forth the actual annual incentive awarded to each of our NEOs under the Senior Executive Incentive Compensation Plan for the year:

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Long-Term Leadership Performance Program under Our Shareholder-Approved Plan

The LPP is a sub-plan of our Shareholder-Approved Plan, which means that LPP awards are subject to plan terms approved by our shareholders. Each annual award granted under the LPP consists of PSUs that are eligible to vest over a three-year performance period based on achievement of cumulative adjusted diluted earnings per share targets over that period. The Compensation Committee historically has approved LPP awards for our NEOs each year. The three-year LPP performance cycles run concurrently, so we may have up to three active cycles during a given year. For example, during 2024, the three active cycles were LPP 17, LPP 18, and LPP 19 (for the 2022-2024, 2023-2025, and 2024-2026 performance periods, respectively). This design is intended to ensure that our NEOs remain focused on long-term sustainable performance while providing the Compensation Committee with the ability to evaluate performance metrics on a regular basis. We do not pay dividends or credit dividend equivalents on PSUs.

During the first quarter of 2024, we granted PSUs to our executive officers, including each NEO (other than Mr. Reese, who joined the Company in July 2024 and received his grant at that time), pursuant to LPP 19 (2024-2026 performance period). During the first quarter of 2025, we determined our actual levels of achievement under LPP 17 (2022-2024 performance period) and granted PSUs under LPP 20 (2025-2027 performance period).

LPP Awards Granted in 2024

LPP 19 (2024 Grant for 2024-2026 Performance Period). This is our regular three-year performance cycle for long-term incentive awards granted annually to our most senior leaders. The LPP is intended to further strengthen the relationship between wealth accumulation for our executives and long-term financial performance of the Company and increase in shareholder value, and the PSUs awarded under LPP are payable (to the extent earned) in the form of Class A Ordinary Shares. The grant date value of the awards (at target) was determined and approved by the Compensation Committee (and, with respect to Mr. Case, the independent members of the Board). From that value, the number of target PSUs was calculated on the date of grant based on that day’s closing price for Class A Ordinary Shares on NYSE. The PSUs under LPP 19 will be earned and settled in a range of 0% (if the threshold level of performance is not achieved) to 200% of the target number of shares (if the maximum level of performance is achieved) based on the Company’s cumulative adjusted diluted earnings per share over the three-year performance period.

The performance results for LPP 19 will be measured against the three-year publicly reported cumulative adjusted diluted earnings per share target rate, subject to limited adjustments set forth in the plan documentation at the beginning of the three-year period. The adjustments are intended to exclude the impact of material and/or significant items, to provide a target that, while challenging, eliminates the impact of certain events and circumstances outside of the control of the relevant executive officers. The Compensation Committee’s selection under LPP 19 of the three-year performance period and cumulative adjusted diluted earnings per share financial performance metric is intended to provide the award recipients a reasonable period within which to achieve and sustain what are intended to be challenging long-term growth objectives. The Compensation Committee believes adjusted diluted earnings per share is a more effective measure of Company performance for purposes of motivating executive performance than diluted earnings per share calculated in accordance with U.S. GAAP, as the adjusted measure provides a target that is more within the executives’ control and area of accountability. Further, the Company believes that adjusted diluted earnings per share provides a perspective on the Company’s ongoing core operating performance that is consistent with how shareholders measure our success and that creates transparency and clarity for participants. We generally do not disclose forward-looking goals for our multi-year LPP grants, because the Company does not provide forward-looking guidance to our investors with respect to adjusted diluted earnings per share for multi-year periods and it is competitively sensitive information. Consistent with our past and current practice, we will disclose multi-year performance goals in our regular programs in full after the close of the performance period.

In determining the individual awards under LPP 19 granted in the first quarter of 2024, the Compensation Committee (and, with respect to Mr. Case, the independent members of the Board) considered internal pay relationships, the award recipient’s compensation mix, and total direct compensation, including the recipient’s total direct compensation for 2023 relative to similarly situated executives at our 2024 peer group members. Mr. Reese’s LPP 19 grant was made at the time he commenced employment and the size of such grant was based on similar factors as well as his compensation from his prior employer. For further information regarding individual awards under LPP 19, see footnote (1) in the Summary Compensation Table below, and the Grants of Plan-Based Awards in Fiscal Year 2024 Table below.

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LPP Awards Earned in 2024

LPP 17 (2022 Grant for 2022-2024 Performance Period). In early 2025, we determined the actual achievement under LPP 17. The performance period for LPP 17 ended on December 31, 2024.

LPP 17 PSUs (Performance Period 1/1/2022—12/31/2024)

For LPP 17, the cumulative adjusted diluted earnings per share goals from continuing operations ranged from a threshold level of $38.20, below which no payout would occur, to $45.35 or higher, which would yield shares equal to 200% of the target number. A result of $39.72 in cumulative adjusted diluted earnings per share from continuing operations would have yielded shares equal to 100% of the target number. This target performance represented a 22.3% increase over the target for LPP 16, the cycle of our LPP established for the performance period from 2021 through 2023. Our actual cumulative adjusted diluted earnings per share from continuing operations for the three-year period of 2022-2024 was $42.12, resulting in a payout at 163.1% of the target number of shares awarded.

For the 2024 performance period associated with LPP 17, the Compensation Committee approved discretionary adjustments to earnings per share (“EPS”) from continuing operations to exclude the impact of 2024 restructuring savings and adjust for the impact of the NFP transaction, which adjustments are permitted under the terms of the plan. Each NEO other than Mr. Reese received a distribution under LPP 17.

Sign-On Grants

In connection with Mr. Reese’s commencement of employment, in addition to his LPP 19 annual grant, in order to further align his interests with those of our shareholders and to encourage retention and in light of long-term awards that Mr. Reese forfeited from his prior employer, he received a PSU grant pursuant to the LPP that will vest on December 31, 2026 if the pre-established share price hurdle associated with such award is met and he received a grant of RSUs that will vest in equal installments on each of the first three anniversaries of the date of grant. In addition, in consideration of forfeitures from prior employment, Mr. Reese also received a deferred cash sign-on bonus in the amount of $1,000,000, payable on or as soon as practicable after completing a year of service (July 1, 2025).

Executive and Relocation Benefits

Executive Benefits. In addition to the broad-based employee benefit programs that are available to our employees generally (such as health coverage and 401(k) plan), each of our NEOs is eligible to participate in a deferred compensation program and a supplemental savings plan. Only Mr. Andersen participates in our defined benefit pension plan and the supplemental pension program (each of which are frozen to new participation) because each other NEO was hired after the Aon pension plan was closed to new hires in 2004. Additional information regarding these qualified and nonqualified plan benefits is set forth under the headings “Pension Benefits in Fiscal Year 2024” and “Nonqualified Deferred Compensation in Fiscal Year 2024” contained in this proxy statement. We also provide an executive health screening program available to all of our NEOs and certain other members of our senior management team. In 2025, our Board approved a policy for Mr. Case that provides additional access to Aon’s company-paid aircraft, as well as ground travel in Chicago, for approved personal use. This policy is intended to provide advantages in terms of security, time, and productivity and, as a result, is intended to further our business interests.

Relocation Benefits. In 2024, we provided benefits to Mr. Case, Ms. Davies, and Ms. Simon for their agreement to perform services primarily at the Company’s global operational headquarters in London. The Aon group global operational headquarters remained in London following the Company’s reorganization as a public company organized under the laws of Ireland in April 2020, while parent company Aon plc is resident in Dublin. Relocation benefits are customary for expatriate assignments for us and other employers in our industry, and the Compensation Committee approved certain benefits for Mr. Case, Ms. Davies, and Ms. Simon after consulting with its independent compensation consultant. Each relocated NEO has signed an international assignment letter with Aon that sets forth the relocation benefits available to him or her, which are

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described in more detail under the heading “International Assignment Letters.” The Compensation Committee periodically reviews these relocation packages. Ms. Davies’s international assignment ended July 29, 2024.

The compensation received in the form of such benefits is reflected in the Summary Compensation Table for Fiscal Years 2024, 2023, and 2022.

Post-Termination Compensation

We believe that providing severance and change in control severance benefits is important to recruit talented employees and secure the continued employment and dedication of our existing employees. A significant number of the companies with which we compete for talent have similar arrangements in place for their senior executives. While we consider these benefits to be important, the terms of these benefits are not considered as part of the compensation strategy when the Compensation Committee annually determines the compensation for the NEOs. Additional information about post-termination compensation is set forth in the section captioned “Potential Payments and Benefits on Termination or Change in Control” contained in this proxy statement.

Severance Benefits Upon Change in Control. Our NEOs, other than Mr. Case, are eligible for change in control severance benefits under our Senior Executive Combined Severance and Change in Control Plan (referred to throughout this CD&A and the accompanying compensation tables as the “Combined Severance Plan”). The Combined Severance Plan provides that covered executives would receive certain severance benefits upon qualifying terminations of employment in connection with or within two years following a change in control of Aon. Thus, the Combined Severance Plan requires a “double trigger”—a qualifying change in control of Aon and a qualifying termination of the executive’s employment—for severance benefits to become payable. Mr. Case, who is not covered under the Combined Severance Plan, is party to an individual change in control severance agreement with the Company that also provides certain severance benefits upon a qualifying termination in connection with or within two years following a change in control of Aon. Neither the Combined Severance Plan nor Mr. Case’s individual agreement provides for excise tax gross-up protection in the event the executive becomes subject to tax under Section 280G of the Internal Revenue Code of 1986, as amended (the “Code”) in connection with a change in control of Aon.

Additional information regarding the change in control arrangements for our NEOs is set forth in the section captioned “Potential Payments and Benefits on Termination or Change in Control” contained in this proxy statement.

Severance Benefits Pursuant to Employment Agreements and Combined Severance Plan; Transition Agreement. We have entered into agreements with certain executive officers that provide for post-employment severance benefits and transitional compensation if the officer’s employment terminates for a qualifying event or circumstance unrelated to a change in control of Aon, such as being terminated without “cause,” as such term is defined in the applicable operative agreement.

In the case of Mr. Andersen, we entered into an employment agreement with him on July 26, 2023, pursuant to which he continued to serve as President of the Company and Aon Corporation. Additional information about Mr. Andersen’s employment agreement is provided in the section captioned “Summary Compensation Table for Fiscal Years 2024, 2023 and 2022” in this proxy statement under “Mr. Andersen’s Employment Agreement” and in the section captioned “Potential Payments and Benefits on Termination or Change in Control” under “Employment Agreement with Mr. Andersen.” Effective March 14, 2025, the Company removed Mr. Andersen from the role of President, and he transitioned to the role of senior advisor for the remainder of the employment term (June 30, 2026) pursuant to his employment agreement. A discussion of Mr. Andersen’s employment agreement appears on page 54.

In the case of Ms. Davies, we entered into an employment transition agreement whereby Ms. Davies ceased to serve as Chief Financial Officer effective July 29, 2024, pursuant to her transition agreement, and she transitioned to the role of senior advisor through May 31, 2026. (For additional detail, see “Ms. Davies’s Employment Agreement and Transition Agreement” on page 53 and “Employment Agreement and Transition Agreement with Ms. Davies” on page 67.)

To the extent that our NEOs are not party to an individual employment agreement providing for severance benefits, those individuals are eligible to receive severance benefits under the Combined Severance Plan. During 2024, each of our NEOs had an employment agreement or letter providing for severance benefits or was eligible to receive severance benefits under the Combined Severance Plan (with Ms. Davies entering into a transition agreement effective July 2024). Additional information regarding such post-employment severance or transitional compensation for Mr. Case and the other NEOs is set forth in the section captioned “Potential Payments and Benefits on Termination or Change in Control” contained in this proxy statement.

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Risk Assessment of Compensation Policies and Practices

We believe that we maintain an appropriate level of prudence associated with our compensation practices and will continue to do so. We engage in a process to evaluate whether our executive and broad-based compensation programs contribute to unnecessary risk-taking. This includes a detailed annual assessment by the Compensation Committee’s independent consultant. We concluded that the risks arising from these programs are not reasonably likely to have a material adverse effect on the Company. In the first quarter of 2025, Meridian independently assessed our compensation practices for 2024 and concluded that they reflect appropriate balance and incorporate appropriate policies and oversight to mitigate imprudent risk-taking.

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Compensation Committee Report

The Organization and Compensation Committee of the Board has reviewed and discussed with management the Compensation Discussion and Analysis required by Item 402(b) of Regulation S-K and set forth in this proxy statement.

Based on its review and discussions with management, the Organization and Compensation Committee recommended to the Board that the Compensation Discussion and Analysis be included in this proxy statement and thereby incorporated into Aon’s Annual Report on Form 10-K for the year ended December 31, 2024.

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Executive Compensation

The executive compensation disclosure contained in this section reflects compensation information for the years ended December 31, 2024, December 31, 2023, and December 31, 2022, with respect to our NEOs for all years in which each NEO served in that capacity. The following Summary Compensation Table contains compensation information for the following NEOs: (1) Mr. Case, who served as our Chief Executive Officer during 2024; (2) Mr. Reese, who joined the Company as our Chief Financial Officer in July 2024; (3) Ms. Davies, who served as our Chief Financial Officer until July 29, 2024 and has since entered into a transition agreement; and (4) Mr. Andersen, who served as our President during 2024 and has since transitioned to a senior advisor position, Ms. Stevens, and Ms. Simon, who were our three other most highly compensated executive officers serving as of December 31, 2024.

Summary Compensation Table for Fiscal Years 2024, 2023 and 2022

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