6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 6-K

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

For the month of July 2025

Commission File Number: 001-31909

ASPEN INSURANCE HOLDINGS LIMITED

(Translation of registrant’s name into English)

141 Front Street

Hamilton HM 19

Bermuda

(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  ý Form 40-F  ¨

On July 17, 2025, Aspen Insurance Holdings Limited (“Aspen” or the “Company”) issued a press release announcing the appointment of John Welch as Group Chief Underwriting Officer of the Company, effective August 1, 2025.

The press release, furnished as Exhibit 99.1 to this Form 6-K, is incorporated by reference as part of this Form 6-K.

The information included in this Form 6-K shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

EXHIBIT INDEX

Exhibit

99.1        Press Release dated July 17, 2025

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.

Document

Exhibit 99.1

Aspen Appoints John Welch as Group Chief Underwriting Officer

HAMILTON, Bermuda--(BUSINESS WIRE)--Aspen Insurance Holdings Limited (“Aspen”) (NYSE: AHL) has appointed John Welch as Group Chief Underwriting Officer.

John brings over 30 years of experience in executive roles across global players including at AXA XL and XL Catlin Group, and originally joined Aspen as Chief Underwriting Officer, Reinsurance in June 2023.

In his new role, which is effective from August 1, 2025, John will report into Group President and CEO, Aspen Bermuda Limited, Christian Dunleavy, and will be responsible for the oversight, development and execution of Aspen’s underwriting strategy across the Group.

Christian Dunleavy said, “John’s promotion reflects his broad and deep expertise and experience and further strengthens the underwriting and leadership capabilities that underpin Aspen’s continued success and our ability to serve our customers, trading partners and investors alike.”

About Aspen Insurance Holdings Limited (“Aspen” or the “Company”)

Aspen provides insurance and reinsurance coverage to clients in various domestic and global markets through wholly-owned operating subsidiaries in Bermuda, the United States and the United Kingdom, as well as its branch operations in Canada, Singapore and Switzerland. For more information about Aspen, please visit www.aspen.co.

Contacts

For further information:

Media

Cecile Locurto

Vice President, Aspen Group Communications

Cecile.locurto@aspen.co

+1 646 352 2828

Tom Blackwell

Managing Director, FTI Consulting

Tom.Blackwell@fticonsulting.com

+44 (0)7747 113 919