AON Aon PLC

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

If this form relates to the registration of a class of securities pursuant to Section 12(b) of the Exchange Act and is effective pursuant to General Instruction A.(c), check the following box.  ☒

If this form relates to the registration of a class of securities pursuant to Section 12(g) of the Exchange Act and is effective pursuant to General Instruction A.(d), check the following box.  ☐

If this form relates to the registration of a class of securities concurrently with a Regulation A offering, check the following box.  ☐

Securities Act registration statement or Regulation A offering statement file number to which this form relates (if applicable): 333-238189

Securities to be registered pursuant to Section 12(g) of the Act: None.

Item 1. Description of Registrant’s Securities to be Registered.

Aon Corporation (“Aon Corp.”) and Aon Global Holdings plc (formerly known as Aon Global Holdings Limited) (“AGH” and, together with Aon Corp., the “Issuers”) register hereunder their 3.900% Senior Notes due 2052 and the guarantees thereof (the “Guarantees” and, together with the Notes, the “Securities”) by each of Aon plc and Aon Global Limited (formerly known as Aon plc) (“AGL”). The information required by this item in respect of the Securities is incorporated herein by reference to the information set forth under the caption “Description of the Securities” in the Issuers’ Prospectus Supplement, dated February 23, 2022, and under the caption “Description of Debt Securities and Guarantees” in the accompanying Prospectus, dated May 12, 2020, filed with the Securities and Exchange Commission (the “Commission”) on February 25, 2022 and May 12, 2020, respectively.

SIGNATURE

Pursuant to the requirements of Section 12 of the Securities Exchange Act of 1934, the registrants have duly caused this registration statement to be signed on their behalf by the undersigned, thereto duly authorized.

Dated: February 28, 2022