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 October 2025

Commission File Number: 001-40777

ARQIT QUANTUM INC.

(Exact name of registrant as specified in its charter)

1^st Floor, 3 Orchard Place

London, SW1H 0BF United Kingdom

(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 ¨

EXPLANATORY NOTE

On October 9, 2025 Arqit Quantum Inc. (the “Company”) issued a press release entitled “Announces Select Preliminary Financial Results for the Second Half and Full Fiscal Year 2025,” in which the Company reported select unaudited preliminary financial results for the six months and year ended September 30, 2025. A copy of that press release is furnished as Exhibit 99.1 hereto.

The information furnished in this Report of Foreign Private Issuer on Form 6-K, including the information contained in Exhibit 99.1, shall not be deemed to be “filed” for the purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, and shall not be deemed to be incorporated by reference into any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by a specific reference in such filing.

EXHIBIT INDEX

Exhibit No.		Description
99.1		Press release of Arqit Quantum Inc., dated October 9, 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.

ARQIT QUANTUM INC.

By:	/s/ Andrew Leaver
Name:	Andrew Leaver
Title:	Chief Executive Officer

Date: October 9, 2025

Arqit Quantum Inc. 6-K