6-K

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

October 16, 2025

Commission FileNumber 1-10167

WESTPAC BANKING CORPORATION

(Translation of registrant’s name into English)

275 KENT STREET, SYDNEY, NEW SOUTH WALES 2000, AUSTRALIA

(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 ¨

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): ¨

Index to Exhibits

Disclosure regarding forward-looking statements

The information contained in this Report on Form 6-K contains statements that constitute “forward-looking statements” within the meaning of section 21E of the U.S. Securities Exchange Act of 1934.

Forward-looking statements are statements that are not historical facts. Forward-looking statements appear in a number of places in this Report and include statements regarding our current intent, belief or expectations with respect to our business and operations, macro and micro economic and market conditions, results of operations and financial condition and performance, capital adequacy and liquidity and risk management, including, without limitation, future loan loss provisions and financial support to certain borrowers, forecasted economic indicators and performance metric outcomes, indicative drivers, climate- and other sustainability-related statements, commitments, targets, projections and metrics, and other estimated and proxy data.

Words such as ‘will’, ‘may’, ‘expect’, ‘intend’, ‘seek’, ‘would’, ‘should’, ‘could’, ‘continue’, ‘plan’, ‘estimate’, ‘anticipate’, ‘believe’, ‘probability’, ‘indicative’, ‘risk’, ‘aim’, ‘outlook’, ‘forecast’, ‘assumption’, ‘projection’, ‘target’, ‘goal’, ‘guidance’, ‘objective’, ‘ambition’ or other similar words, are used to identify forward-looking statements. These statements reflect our current views on future events and are subject to change, certain known and unknown risks, uncertainties and assumptions and other factors which are, in many instances, beyond our control (and the control of our officers, employees, agents and advisors), and have been made based on management’s current expectations or beliefs concerning future developments and their potential effect upon Westpac.

Forward-looking statements may also be made, verbally or in writing, by members of Westpac’s management or Board in connection with this Report. Such statements are subject to the same limitations, uncertainties, assumptions and disclaimers set out in this Report.

There can be no assurance that future developments or performance will align with our expectations or that the effect of future developments on us will be those anticipated. Actual results could differ materially from those we expect or which are expressed or implied in forward-looking statements, depending on various factors including, but not limited to, those described in the section titled ‘Risk factors’ in Westpac’s 2025 Interim Financial Results on Form 6-K filed with the U.S. Securities and Exchange Commission. When relying on forward-looking statements to make decisions with respect to us, investors and others relying on information in this Report should carefully consider such factors and other uncertainties and events.

Except as required by law, we assume no obligation to revise or update any forward-looking statements in this Report, whether from new information, future events, conditions or otherwise, after the date of this Report.

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, thereunto duly authorized.

Exhibit 1

16 October 2025

ITEMS IMPACTING WESTPAC’SFULL YEAR 2025 (FY25) RESULTS

Items included within OperatingExpenses in Second Half 2025 (2H25)

The Group has recognised a restructuring charge of $273 million (pre-tax) as part of the targeted productivity initiatives through our Fit for Growth Program.

Productivity benefits are expected to be commensurate with the expense. Modest benefits were delivered in FY25, with the majority to be realised during FY26 and FY27.

The expense, which will not be treated as a Notable Item, will be included in operating expenses for 2H25. The full amount will be reported in Group Businesses.

Segment composition

In 2025, the composition of our segments was revised to improve operational alignment. The key changes include:

1H25 has been restated for the above changes. FY24 has not been restated. The restated 1H25 segments are included in the 2025 Full Year Results Announcement pro-forma.

These changes do not impact the Group's net profit after tax (NPAT) or the composition of line items.

Reporting changes and NotableItems

A 2025 Full Year Results Announcement will be lodged alongside the Annual Report to assist with analysing performance. This document will include tables and commentary comparing the full and half year results along with additional disclosure on 'Net profit excluding Notable Items'. This measure is comparable to 'cash earnings'.

Hedging Notable Items will not be pre-released in future periods. For completeness, Westpac’s reported net profit after tax in FY25 will be reduced by $56 million due to Notable Items that relate solely to hedging items, which reverse over time. This compares to a $123 million reduction in FY24. A summary of the impacts in FY25 are included in Appendix 1.

A pro-forma document can be found on our website at: https://www.westpac.com.au/about-westpac/ investor-centre/events-and-presentations/presentations-agm/

Full Year 2025 results are scheduled to be announced on Monday, 3 November 2025.

For further information:

This document has been authorised for release by Tim Hartin, Company Secretary.

Appendix 1 - Summary of Notable Items

This announcement is unaudited. All amounts are in Australian dollars. Net Profit excluding Notable Items is not defined by Australian Accounting Standards (AAS). These non-AAS measures are identified and described in the ‘Introduction – Non-AAS financial measures’ section in the 2025 Interim Financial Results.

This announcement contains ‘forward-looking statements’ and statements of expectation reflecting Westpac’s current views on future events. They are subject to change without notice and certain risks, uncertainties and assumptions which are, in many instances, beyond its control. They have been based upon management's expectations and beliefs concerning future developments and their potential effect on Westpac. Should one or more of the risks or uncertainties materialise, or should underlying assumptions prove incorrect, actual results may differ materially from those expressed or implied in such statements. Investors should not place undue reliance on forward-looking statements and statements of expectation. Except as required by law, Westpac is not responsible for updating, or obliged to update, any matter arising after the date of this announcement. The information in this announcement is subject to the information in Westpac’s ASX filings.