Results of Operations

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM  8-K   CURRENT REPORT Pursuant to Section 13 or 15(d)  of the Securities Exchange Act of 1934   Date of report (Date of earliest event reported): April 25, 2025 Aon plc (Exact Name of Registrant as Specified in Charter) Ireland   1-7933   98-1539969 (State or Other Jurisdiction of Incorporation)   (Commission File Number)   (IRS Employer Identification No.) 15 George's Quay , Dublin 2 , Ireland        D02 VR98 (Address of principal executive offices)   (Zip Code)                       Registrant’s telephone number, including area code: + 353 1 266 6000   Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions ( see General Instruction A.2. below):   o     Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)   o     Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)   o     Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))   o     Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each class Trading Symbol(s) Name of each exchange on which registered Class A Ordinary Shares $0.01 nominal value AON New York Stock Exchange Guarantees of Aon plc’s 3.875% Senior Notes due 2025 AON25 New York Stock Exchange Guarantees of Aon plc’s 2.875% Senior Notes due 2026 AON26 New York Stock Exchange Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.850% Senior Notes due 2027 AON27 New York Stock Exchange Guarantees of Aon North America, Inc.'s 5.125% Senior Notes due 2027 AON27B New York Stock Exchange Guarantees of Aon North America, Inc.'s 5.150% Senior Notes due 2029 AON29 New York Stock Exchange Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.050% Senior Notes due 2031 AON31 New York Stock Exchange Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.600% Senior Notes due 2031 AON31A New York Stock Exchange Guarantees of Aon North America, Inc.'s 5.300% Senior Notes due 2031 AON31B New York Stock Exchange Guarantees of Aon Corporation and Aon Global Holdings plc’s 5.000% Senior Notes due 2032 AON32 New York Stock Exchange Guarantees of Aon Corporation and Aon Global Holdings plc's 5.350% Senior Notes due 2033 AON33 New York Stock Exchange Guarantees of Aon North America, Inc.'s 5.450% Senior Notes due 2034 AON34 New York Stock Exchange Guarantees of Aon plc’s 4.250% Senior Notes due 2042 AON42 New York Stock Exchange Guarantees of Aon plc’s 4.450% Senior Notes due 2043 AON43 New York Stock Exchange Guarantees of Aon plc’s 4.600% Senior Notes due 2044 AON44 New York Stock Exchange Guarantees of Aon plc’s 4.750% Senior Notes due 2045 AON45 New York Stock Exchange Guarantees of Aon Corporation and Aon Global Holdings plc’s 2.900% Senior Notes due 2051 AON51 New York Stock Exchange Guarantees of Aon Corporation and Aon Global Holdings plc’s 3.900% Senior Notes due 2052 AON52 New York Stock Exchange Guarantees of Aon North America, Inc.'s 5.750% Senior Notes due 2054 AON54 New York Stock Exchange Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company o If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o 2 Item 2.02.             Results of Operations and Financial Condition.   On April 25, 2025, Aon plc issued a press release (the “Press Release”) announcing its results of operations for the quarter ended March 31, 2025.   A copy of the Press Release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.   Item 9.01.             Financial Statements and Exhibits.   (a) - (c)   Not applicable.   (d)           Exhibits: Exhibit Number   Description of   Exhibit 99.1   Press Release issued by Aon plc on April 25, 2025. 104 Cover Page Interactive Data File (formatted as Inline XBRL) 3 SIGNATURES   Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.      Aon plc       By: /s/ Michael Neller     Michael Neller     Senior Vice President, Global Controller and Chief Accounting Officer     Date: April 25, 2025     4