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): October 31, 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

Item 2.02. Results of Operations and Financial Condition.

On October 31, 2025, Aon plc issued a press release (the “Press Release”) announcing its results of operations for the quarter ended September 30, 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 October 31, 2025.

104

Cover Page Interactive Data File (formatted as Inline XBRL)

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/ David DeBrunner
			David DeBrunner
			Senior Vice President, Global Controller and Chief Accounting Officer

Date:	October 31, 2025

Aon plc 8-K