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 October 2025

Commission File Number: 001-41369

Osisko Development Corp. (Translation of registrant's name into English)

1100 Avenue des Canadiens-de-Montréal, Suite 300, Montréal, Quebec H3B 2S2 (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 [ X ]

EXHIBIT INDEX

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.

Exhibit 99.1

OSISKO DEVELOPMENT CLOSES C$82.5 MILLION PRIVATE PLACEMENT

Montreal, Québec, October 29, 2025 – Osisko DevelopmentCorp. (NYSE: ODV, TSXV: ODV) ("Osisko Development" or the "Company") is pleased to announce the successful closing of its previously-announced oversubscribed private placement offering of 15,409,798 common shares of the Company (the "Common Shares") for aggregate gross proceeds of approximately C$82.5 million (the "Offering").

The Offering is comprised of the following issuances, on a private placement basis:

The Company will use an amount equal to the aggregate gross proceeds from the sale of the Flow-Through Shares under the Offering to incur eligible "Canadian exploration expenses" that will qualify as (i) "flow-through mining expenditures" within the meaning of the Tax Act, and (ii) in respect of the BC FT Shares purchased by eligible British Columbia purchasers, "BC flow-through mining expenditures" that meet the criteria set forth in subsection 4.721(1) of the Income Tax Act (British Columbia), in respect of the exploration activities on the Company's properties in British Columbia (the "QualifyingExpenditures"). The Qualifying Expenditures will be incurred on or before December 31, 2026 and will be renounced by the Company to the initial purchasers of the Flow-Through Shares with an effective date no later than December 31, 2025.

The Company intends to use the net proceeds of the Common Shares issued pursuant to the Offering to contribute to the capital required to construct the Cariboo Gold Project and related pre-construction activities.

In connection with the Offering, the underwriters for the Offering were paid a cash commission equal to 4.5% of the aggregate gross proceeds of the Offering.

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The Common Shares issued under the Concurrent Private Placement will be subject to a statutory hold period of four months and one day pursuant to applicable Canadian securities laws. The Offering remains subject to final acceptance of the TSX Venture Exchange.

Insider Participation

Double Zero Capital LP ("Double Zero"), which is an "insider" of the Company, have subscribed for 2,447,775 Common Shares at a price of C$4.78 for gross proceeds of C$11,700,365 (the "DoubleZero Subscription") pursuant to its pre-emptive rights in respect of the Offering under the investor rights agreement dated August 15, 2025 between Double Zero and the Company. The Double Zero Subscription is considered to be a "related party transaction" for the purposes of Multilateral Instrument 61-101 – Protection of Minority Security Holders in Special Transactions ("MI 61-101"). The Company did not file a material change report more than 21 days before the expected closing date of the Offering as the details of the Offering and the Double Zero Subscription was not settled until shortly prior to the closing of the Offering, and the Company wished to close the Offering on an expedited basis for sound business reasons. The Company is relying on exemptions from the formal valuation and minority shareholder approval requirements available under MI 61-101. The Company is exempt from the formal valuation requirement in section 5.4 of MI 61-101 in reliance on section 5.5(a) of MI 61-101 as the fair market value of the transaction, insofar as it involves interested parties, is not more than 25% of the Company's market capitalization. Additionally, the Company is exempt from minority shareholder approval requirement in section 5.6 of MI 61-101 in reliance on section 5.7(1)(a) of MI 61-101 as the fair market value of the transaction, insofar as it involves interested parties, is not more than 25% of the Company's market capitalization.

This news release does not constitute an offer to sell ora solicitation of an offer to buy any of the securities described herein in the United States. The securities described herein have notbeen and will not be registered under the U.S. Securities Act of 1933, as amended (the "U.S. Securities Act"), or any U.S. statesecurities laws, and may not be offered or sold in the United States absent registration under the U.S. Securities Act and all applicableU.S. state securities laws or in compliance with an exemption therefrom.

ABOUT OSISKO DEVELOPMENT CORP.

Osisko Development Corp. is a continental North American gold development company focused on past-producing mining camps located in mining friendly jurisdictions with district scale potential. The Company's objective is to become an intermediate gold producer by advancing its flagship permitted 100%-owned Cariboo Gold Project, located in central B.C., Canada. Its project pipeline is complemented by the Tintic Project in the historic East Tintic mining district in Utah, U.S.A., and the San Antonio Gold Project in Sonora, Mexico—brownfield properties with significant exploration potential, extensive historical mining data, access to existing infrastructure and skilled labour. The Company's strategy is to develop attractive, long-life, socially and environmentally responsible mining assets, while minimizing exposure to development risk and growing mineral resources.

For further information, visit our website at www.osiskodev.com or contact:

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CAUTION REGARDING FORWARD-LOOKING STATEMENTS

This news release contains "forward-looking information"(within the meaning of applicable Canadian securities laws) and "forward- looking statements" (within the meaning of the U.S. PrivateSecurities Litigation Reform Act of 1995). Such statements or information are identified with words such as "anticipate", "believe","expect", "plan", "intend", "potential", "estimate", "propose", "project", "outlook", "foresee" or similar words suggesting future outcomesor statements regarding any potential outcome. Such statements in this news release may include, without limitation, statements pertainingto: the use of the proceeds of the Offering, the tax treatment of the Flow-Through Shares, the timing and ability of the Company to renouncethe Qualifying Expenditures and the ability to obtain the necessary regulatory authority approvals, the ability to obtain the final acceptanceof the TSX Venture Exchange and/or the New York Stock Exchange and the Company's strategy and objectives relating to the Cariboo GoldProject as well as its other projects. Such forward-looking information or statements are based on a number of risks, uncertainties andassumptions which may cause actual results or other expectations to differ materially from those anticipated and which may prove to beincorrect. Actual results could differ materially due to a number of factors, including, without limitation, satisfying the requirementsof the New York Stock Exchange and the TSX Venture Exchange (if at all), risks related to exploration, development and operation of theCariboo Gold Project, general economic and market conditions and business conditions in the mining industry, fluctuations in commodityand currency exchange rates, changes in regulatory framework and applicable laws, as well as those risks and factors as disclosed inthe Company's most recent annual information form, financial statement and management's discussion and analysis as well as other publicfilings on SEDAR+ (www.sedarplus.ca). Although the Company believes that the expectations reflected in the forward-looking informationor statements are reasonable, prospective investors in the Company securities should not place undue reliance on forward-looking statementsbecause the Company can provide no assurance that such expectations will prove to be correct. Forward-looking information and statementscontained in this news release are as of the date of this news release and the Company assumes no obligation to update or revise thisforward-looking information and statements except as required by law.

Neither the TSX Venture Exchange nor its Regulation ServicesProvider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy ofthis news release. No stock exchange, securities commission or other regulatory authority has approved or disapproved the informationcontained herein.