UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 8-A

FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
PURSUANT TO SECTION 12(b) OR (g) OF THE
SECURITIES EXCHANGE ACT OF 1934

Securities to be registered pursuant to Section 12(b) of the Act:

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.  x

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.  o

Securities Act registration statement file number to which this form relates:  333-183686

Securities to be registered pursuant to Section 12(g) of the Act:

None

(Title of class)

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

For a description of the securities to be registered hereunder, reference is made to the information under the headings “Description of the Securities” on pages S-17 through S-23 of the Prospectus Supplement dated May 13, 2015 and “Description of Debt Securities and Guarantees” on pages 10 through 26 of the Prospectus dated August 31, 2012, each of which forms part of the registration statement on Form S-3 (Registration Statement No. 333-183686) of Aon plc, which information is incorporated by reference and made part of this registration statement in its entirety.

Item 2.                                                         Exhibits.

The securities to be registered hereunder are expected to be listed on the New York Stock Exchange, the exchange on which certain other securities of Aon plc are currently listed. Pursuant to the Instructions as to Exhibits with respect to Form 8-A, the following exhibits are being filed with the Securities and Exchange Commission in connection with this Registration Statement:

1.1                                     Prospectus Supplement dated May 13, 2015 and Prospectus dated August 31, 2012 (incorporated by reference to the filing under Rule 424(b)(5) (Registration Statement No. 333-183686) filed by Aon plc on May 14, 2015)

1.2                                     Amended and Restated Indenture dated as of May 20, 2015 between Aon plc, Aon Corporation and The Bank of New York Mellon Trust Company, N.A. (incorporated by reference to Exhibit 4.1 of the Current Report on Form 8-K filed by Aon plc on May 20, 2015)

1.3                                     Form of 4.750% Senior Note due 2045 (incorporated by reference to Exhibit 4.2 of the Current Report on Form 8-K filed by Aon plc on May 20, 2015)

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SIGNATURE

Pursuant to the requirements of Section 12 of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized.

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EXHIBIT INDEX

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