Exhibit 5.1

April 8, 2022

Star Bulk Carriers Corp.

c/o Star Bulk Management Inc.
40 Agiou Konstantinou Street
15124 Maroussi, Athens, Greece

Ladies and Gentlemen:

We have acted as counsel to Star Bulk Carriers Corp. (the "Company") in connection with (i) the Company's at-the-market offering (the "Offering") of shares of its common stock, par value $0.01 per share, having an aggregate offering price of up to $63,084,580 (the "Shares"); (ii) the Amended and Restated At-The-Market Sales Agreement, dated April 8, 2022 (the "Sales Agreement"), between the Company and Deutsche Bank Securities Inc.  as sales agent, including any amendments or supplements thereto, pursuant to which the Company may offer the Shares through the Agent, from time to time; (iii) the preparation of the Company's registration statement on Form F-3 (File No.333-264226), which was filed on April 8, 2022 with the Securities and Exchange Commission (the "Commission") (the "Registration Statement"), including a prospectus included therein (the "Base Prospectus") and a prospectus supplement dated April 8, 2022 (the "Prospectus Supplement" and together with the Base Prospectus, the "Prospectus").

We have examined originals or copies, certified or otherwise identified to our satisfaction, of: (i) the Sales Agreement, (ii) the Registration Statement, (iii) the Base Prospectus, (iv) the Prospectus Supplement and (vi) such corporate documents and records of the Company and such other instruments, certificates and documents as we have deemed necessary or appropriate as a basis for the opinions hereinafter expressed. In such examinations, we have assumed the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as copies or drafts of documents to be executed, the genuineness of all signatures and the legal competence or capacity of persons or entities to complete the execution of documents. As to various questions of fact that are material to the opinions hereinafter expressed, we have relied upon statements or certificates of public officials, directors of the Company and others.

We have further assumed for the purposes of this opinion, without investigation, that (i) all documents contemplated by the Prospectus to be executed in connection with the Offering have been duly authorized, executed and delivered by each of the parties thereto other than the Company, and (ii) the terms of the Offering comply in all respects with the terms, conditions and restrictions set forth in the Prospectus and all of the instruments, agreements and other documents relating thereto or executed in connection therewith.

In connection with our opinion expressed below, we have assumed that, at or prior to the time of the delivery of any of the Shares, there will not have occurred any change in the law or the facts affecting the validity of the Shares.

With respect to the Shares, we have assumed that, as of each and every time any of the Shares are issued in accordance with the Sales Agreement, the Company will have a sufficient number of authorized and unissued Shares available for issuance under its Fourth Amended and Restated Articles of Incorporation, as amended.

Based upon and subject to the foregoing, and having regard to such other legal considerations which we deem relevant, we are of the opinion that:

The foregoing opinions are subject in each case to applicable insolvency, bankruptcy, reorganization, moratorium, fraudulent transfer, fraudulent conveyance or other similar laws affecting generally the enforceability of creditors' rights from time to time in effect and subject to general principles of equity, regardless of whether considered in a proceeding in equity or at law, including application of principles of good faith, fair dealing, commercial reasonableness, materiality, unconscionability and conflict with public policy and other similar principles.

This opinion is limited to the laws of the State of New York, the federal laws of the United States of America, and the laws of the Republic of the Marshall Islands as in effect on the date hereof.

We hereby consent to the filing of this opinion as an exhibit to the Company's Report on Form 6-K to be filed with the Commission on or about the date hereof, and to each reference to us and the discussions of advice provided by us under the headings "Legal Matters" in the Prospectus, without admitting we are "experts" within the meaning of the Securities Act of 1933, as amended, or the rules and regulations of the Commission promulgated thereunder with respect to any part of the Registration Statement or Prospectus.

Very truly yours,

/s/ Seward & Kissel LLP