Osisko Development Corp. — Capital/Financing Update 2023

Feb 10, 2023

OSISKO DEVELOPMENT CORP. BOUGHT PUBLIC OFFERING OF UNITS

AMENDED TERM SHEET

FEBRUARY 10, 2023

A preliminary short form prospectus containing important information relating to the securities described in this document has not yet been filed with the securities regulatory authorities in each of the provinces of Canada. A copy of the preliminary short form prospectus is required to be delivered to any investor that received this document and expressed an interest in acquiring the securities. Copies of the preliminary short form prospectus may be obtained from Eight Capital at ecm@viicapital.com. There will not be any sale or any acceptance of an offer to buy the securities until a receipt for the final short form prospectus has been issued.

This document does not provide full disclosure of all material facts relating to the securities offered. Investors should read the preliminary short form prospectus, final short form prospectus and any amendment, for disclosure of those facts, especially risk factors relating to the securities offered, before making an investment decision.

The securities offered under this short form prospectus have not been and will not be registered under the United States Securities Act of 1933, as amended (the "U.S. Securities Act"), or any state securities laws. Accordingly, the securities offered hereby may not be offered, sold or delivered, directly or indirectly, within the United States of America, its territories and possessions, any state of the United States or the District of Columbia (the "United States"), or to any U.S. person (as defined in regulation S under the U.S. Securities Act) except in transactions exempt from registration under the U.S. Securities Act and under the securities laws of any applicable state.

Issuer: Osisko Development Corp. (the "Company")

Issue: Treasury offering of 6,819,000 units ("Units"). Each Unit shall be comprised of one common share in the capital of the Company (a "Share") and one common share purchase warrant (a "Warrant"). Each Warrant shall entitle the holder thereof to purchase one Share, at an exercise price of $8.55, for period of 36 months from the Closing Date.

Issue Price: $6.60 per Unit

Issue Size: $45,005,400

Underwriters' Option: The Company has granted the Underwriters an option to purchase up to an additional 15% of the Units and/or the components thereof, exercisable in whole or in part at any time for a period of 30 days after and including the Closing Date.

Use of Proceeds: The net proceeds of the Offering will be used principally to advance the development of the Company's material mining projects, and for general corporate purposes as set out in the short form prospectus.

Form of Underwriting: Bought deal, subject to termination clauses including "material adverse change" out, "disaster" out, and "breach" out.

Form of Offering: Public offering in all provinces of Canada, by way of a short form prospectus.

Private placement in the United States and to U.S. persons pursuant to exemptions from the registration requirements of the U.S. Securities Act and similar exemptions under the securities laws of any applicable state.

The Offering will also be made available to offshore investors pursuant to relevant prospectus or registration exemptions in accordance with applicable laws.

Listing: The Company's Shares trade on the TSX Venture Exchange ("Exchange") and the New York Stock Exchange (the "NYSE") under the symbol "ODV". The Company will use its best efforts to obtain the necessary approvals to list the Shares on the Exchange and the NYSE, which listings shall be conditions of closing.

VIII EIGHT CAPITAL

NATIONAL BANK

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OSISKO DEVELOPMENT CORP.

BOUGHT PUBLIC OFFERING OF UNITS

Eligibility: The Units will be qualified investments under the Income Tax Act (Canada) for registered accounts.

Underwriters: Eight Capital and National Bank Financial Inc., as co-lead underwriters, on behalf of a syndicate of underwriters.

Commission: 5% cash commission.

Closing Date: On or about March 2, 2023

VIII EIGHT CAPITAL NATIONAL BANK