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 OF

THE SECURITIES EXCHANGE ACT OF 1934

For the month of July 2025

Commission File Number: 001-38802

CASTOR MARITIME INC.

(Translation of registrant’s name into English)

223 Christodoulou Chatzipavlou Street, Hawaii Royal Gardens, 3036 Limassol, Cyprus

(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 ☐

INFORMATION CONTAINED IN THIS FORM 6-K REPORT

~~Castor~~Attached ~~Maritime~~to ~~Inc.’s~~this ~~subsidiary,~~report ~~MPCC~~on ~~CSI~~Form ~~LTD.,~~6-K aas ~~company~~Exhibit ~~affiliated~~99.1 ~~with~~is ~~MPC~~a ~~Capital~~copy ~~AG,~~of ~~has~~the ~~acquired~~press ~~3.44%~~release ~~shares~~issued inby ~~MPC~~Castor ~~Container~~Maritime ~~Ships~~Inc. ~~ASA~~ (the “~~MPCC~~Company”), ~~resulting~~on inJuly ~~MPC~~29, ~~Capital AG and its affiliated entities~~2025, ~~collectively~~announcing ~~increasing~~the ~~their~~date ~~holding~~ of ~~total~~its ~~shares~~2025 ~~and~~Annual ~~voting~~General ~~rights~~Meeting ~~in MPCC from approximately 16.68% to 20.12%, or 89,260,056 shares. MPC Capital AG is the founding shareholder~~ of ~~MPCC~~Shareholders.

Attached to this report on Form 6-K as Exhibit 99.12 isare athe ~~copy~~proxy ofmaterials for the ~~notification~~2025 Annual Meeting of ~~major holdings~~Shareholders of the Company.

Attached to this report on Form 6-K as Exhibit 99.3 is the proxy card for the 2025 Annual Meeting of Shareholders of the Company.

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.

	CASTOR MARITIME INC.
Dated: July 7, 2025
Dated: July 29, 2025
	By:	/s/ Petros Panagiotidis
		Petros Panagiotidis
		Chairman, Chief Executive Officer and Chief Financial Officer

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