Company: WEBNF
Filing Date: 2025-07-01
Form Type: 6-K
Source: 0001104659-25-064602
Chunk: 0

Company: WESTPAC BANKING CORP
Filing Date: 2025-07-01
Form: 6-K
Chunk 0
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<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE
13a-16 OR 15d-16
UNDER THE SECURITIES EXCHANGE ACT OF 1934

July 1, 2025

Commission File Number 1-10167

WESTPAC BANKING CORPORATION

(Translation of registrant’s name into English)

(Address of principal executive office)

Indicate by check mark whether the registrant
files or will file annual reports

under cover of Form 20-F or Form 40-F.

Form 20-F x Form 40-F ¨</div>

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ¨

Incorporation by Reference

The exhibits attached to this Report on Form 6-K
shall be incorporated by reference in Westpac Banking Corporation’s (the “”) Registration Statement
on Form F-3 (File No. 333- 283007).

Index to Exhibits

| Exhibit 
 No.     
 1.1     
 4.1     |     | Description                                                                                                                   
 Underwriting Agreement, dated as of June 24, 2025, by and among the Registrant, BofA Securities, Inc., Citigroup Global       
 Markets Inc., J.P. Morgan Securities LLC, Morgan Stanley & Co. LLC and Westpac Banking Corporation.                           
 Thirty-Sixth Supplemental Indenture (including the forms of the Securities), dated as of July 1, 2025, between the Registrant 
 and The Bank of New York Mellon, as trustee.                                                                                  |
|:--------|:----|:------------------------------------------------------------------------------------------------------------------------------|
| 5.1     |     | Opinion of Debevoise & Plimpton LLP.                                                                                          |
| 5.2     |     | Opinion of King & Wood Mallesons.                                                                                             |
| 23.1    |     | Consent                                                                                                                       
 of Debevoise & Plimpton LLP (contained in Exhibit 5.1).                                                                       |
| 23.2    |     | Consent                                                                                                                       
 of King & Wood Malles