Mitesco, Inc.

As filed with the Securities and Exchange Commission on December 31, 2025

Registration No. 333-[______]

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORMS-1

REGISTRATION STATEMENT

UNDER THE SECURITIES ACT OF 1933

Mitesco, Inc.

(Exact name of Registrant as specified in its charter)

505 Beachland Blvd., Suite 1-377

Vero Beach, Florida 32963

(Address, including zip code, and telephone number, including area code, of Registrant’s principal executive offices)

Mack Leath

Chief Executive Officer

Mitesco, Inc.

505 Beachland Blvd., Suite 1-377

Vero Beach, Florida 32963

(844)383-8689

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Joel D. Mayersohn, Esq.

Frank Borger Gilligan, Esq.

350 East Las Olas Blvd.,

Suite 1750,

Ft. Lauderdale FL, 33301

Phone : 954-991-5426

Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this registration statement.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box.☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act of 1933, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act of 1933, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act of 1933, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act of 1934.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.☐

The registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment that specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act, or until the Registration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

EXPLANATORY NOTE AND STATEMENT PURSUANT TO RULE 429

This registration statement on Form S-1 includes a combined prospectus pursuant to Rule 429 under the Securities Act of 1933. The combined prospectus contained herein also relates to the registrant’s previously filed and effective Registration Statement on Form S-1/A (File No. No. 333-286619), which was filed by Mitesco, Inc. (“Mitesco,” the “Company,” “we,” “us,” “our”) with the Securities and Exchange Commission (the “SEC”) on May 14, 2025 and declared effective on May 14, 2025 (the “Original Registration Statement”). In accordance with Rule 429, the combined prospectus included in this filing serves as a post-effective amendment to the Prior Registration Statement.

As of the date of this filing, 105,002,758 of securities registered under the Prior Registration Statement remain unsold. Pursuant to Rule 415(a)(6), the unsold securities from the Prior Registration Statement are being included in this filing serves as a post-effective amendment to the Prior Registration Statement and supersedes the prospectus contained in the Prior Registration Statement.

As the date of this filing,105,002,758 of securities registered under the Prior Registration Statement remain unsold. The filing fee previously paid with respect to such unsold securities will be applied to the securities registered hereby. The Prior Registration Statement will be deemed terminated as the effective date of this registration statement.

The information in this preliminary prospectus is not complete and may be changed. We may not sell these securities until the registration statement related to these securities filed with the Securities and Exchange Commission is declared effective. This prospectus is not an offer to sell or a solicitation of an offer to buy these securities and we are not soliciting offers to buy these securities in any state where the offer or sale is not permitted.

106,836,091 Shares of Common Stock

This prospectus relates to the resale from time to time of up to 106,836,091 shares of common stock, par value $0.01 per share (the “Common Stock”) of Mitesco, Inc. by the Selling Stockholders identified in this prospectus (the “Selling Stockholders”), including their pledgees, assignees, donees, transferees or their respective successors-in interest, consisting of: (i) 2,628,179 shares of Common Stock issued in connection with the restructuring of approximately $12.5 million worth of financial obligations including certain promissory notes, accounts payable, and preferred stock; (ii) 97,779,013 shares of Common Stock issuable upon the mandatory redemption of the newly created Series A Amortizing Convertible Preferred Stock (the “Series A Shares” or “Series A Preferred Stock”), issued to certain institutional investors in exchange for over $14 million worth of its Series D and Series F Preferred Shares, (iii) 2,762,233 shares of Common Stock previously issued in unregistered offerings that the Company has agreed to register on a voluntary basis, and 3,666,666 shares related to the potential conversion of the 2025 Bridge Notes issued on October 31, 2025, and December 22, 2025 respectively.

We are filing this registration statement on Form S-1, of which this prospectus forms a part, to fulfil our contractual obligations to provide for the registration of the resale of the Common Stock. See “Selling Stockholders” beginning on page 37 of this prospectus for more information about the Selling Stockholders. The registration of the shares of Common Stock to which this prospectus relates does not require the Selling Stockholders to sell any of their shares of our Common Stock.

The Stockholders named in this prospectus may offer or sell the shares of Common Stock offered hereby from time to time through public or private transactions at a prevailing market price as quoted on the OTC-QB Venture Market prevailing market prices or at privately negotiated prices. See “Plan of Distribution” on page 49 of the prospectus for more information.

We are not selling any securities under this prospectus and will not receive any of the proceeds from the sale of the shares of our Common Stock.

We are a“smaller reporting company”as defined under the federal securities laws and, as such, have elected to comply with certain reduced public company reporting requirements for this prospectus and may elect to do so in future filings.

Investing in the Common Stock is highly speculative and involves a high degree of risk. You should review carefully the risks and uncertainties described in the section titled “Risk Factors” beginning on page 8 of this prospectus, and under similar headings in any amendments or supplements to this prospectus.

Our Common Stock is currently traded on the OTC-QB Venture Market under the symbol “MITI.” On December 26, 2025, the last reported closing price of our Common Stock was $0.10. There is currently no trading history or market for our Series A Preferred stock.

Neither the Securities and Exchange Commission (the“SEC”) nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is _____________.

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