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 ~~December~~January ~~2025~~2026

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

OnAttached ~~December~~to ~~23,~~this ~~2025,~~report ~~Castor~~on ~~Maritime~~Form ~~Inc.~~6-K ~~(the~~as ~~“Company”~~Exhibit ~~or “Castor”) and Toro Corp~~99.1 ~~(“Toro”)~~is ~~agreed~~a tocopy ~~amend~~of the ~~terms~~press ofrelease ~~(1)~~issued ~~Castor’s 5.00% Series D Cumulative Perpetual Convertible Preferred~~by ~~Shares (the “~~ Castor ~~Series~~Maritime ~~D Preferred Shares”), held by a wholly owned subsidiary of Toro, and (2) Toro’s 1~~Inc.~~00%~~ ~~Series A Fixed Rate Cumulative Perpetual Preferred Convertible Shares~~ (the “~~Toro Series A Preferred Shares~~Company”), ~~held~~on byJanuary ~~a wholly owned subsidiary of Castor~~5, in2026 ~~each~~announcing ~~case to extend~~ the ~~initial~~Company’s ~~conversion~~entry ~~date~~into byan ~~one-year,~~agreement ~~which~~relating ~~shall be~~ to ~~January 1, 2027 in~~ the ~~case~~sale ~~of the Castor Series D Preferred Shares~~ and ~~March~~leaseback ~~7, 2027 in the case~~ of the ~~Toro~~M/V ~~Series~~Magic ~~A Preferred Shares~~Perseus.

~~Toro~~The isinformation acontained ~~public~~in ~~company~~this ~~listed~~report on ~~the~~Form ~~Nasdaq~~6-K ~~Capital Market. Toro’s Chairman~~ and ~~Chief~~Exhibit ~~Executive~~99.1 ~~Officer,~~attached ishereto ~~also~~are ~~Castor’s~~hereby ~~Chairman,~~incorporated ~~Chief~~by ~~Executive~~reference ~~Officer~~into ~~and~~the ~~Chief Financial Officer. The foregoing~~Company’s ~~amendments~~registration tostatements ~~the~~on ~~terms~~Form ofF-3 ~~the~~(File ~~Castor~~Nos. ~~Series~~333-236331, D333-240262 ~~Preferred Shares~~ and the Toro Series A Preferred Shares were approved by the board of directors of Castor and Toro at the recommendation of their respective special committees of disinterested and independent directors who negotiated the amendments333-254977).

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: December 29, 2025
Dated: January 5, 2026
	By:	/s/ Petros Panagiotidis
		Petros Panagiotidis
		Chairman, Chief Executive Officer and Chief Financial Officer
		Chairman, Chief Executive Officer and
		Chief Financial Officer

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