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 August 2025

Commission File Number: 001-39258

BTC Digital Ltd.

61 Robinson Road Level 6 & 7

#738, Singapore 068893

(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 ☒      Form 40-F ☐

Results of 2025 Extraordinary General Meetingof BTC Digital Ltd.

On August 22, 2025, BTC Digital Ltd. (the “Company”) held its 2025 Extraordinary General Meeting (the “Meeting”). The voting results for each of the proposals considered at the Meeting are set forth in Exhibit 99.1 to this Report on Form 6-K.

1

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.

2

EXHIBIT INDEX

3

Exhibit 99.1

BTCDIGITAL LTD.

2025Extraordinary GENERAL MEETING Results

On August 22, 2025, BTC Digital Ltd. (the “Company”) held its 2025 Extraordinary General Meeting (the “Meeting”).

The following are the voting results for the proposals considered and voted upon at the Meeting:

Proposal 1 Approval of an Increase in the Company’sAuthorized Share Capital

Approval of an increase in the Company’s authorized share capital from US$1,500,000, divided into 25,000,000 ordinary shares with a par value of US$0.06 each, to US$12,000,000, divided into 200,000,000 ordinary shares with a par value of US$0.06 each.

Proposal 2 Ratification of Selection of AuditAlliance LLP as Independent Auditor

Ratification of the appointment of Audit Alliance LLP as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2025.

Based on the foregoing votes, the shareholders approved all of the proposals.