Mr. Sean Roosen reports

OSISKO DEVELOPMENT COMPLETES US$143.8 MILLION "BOUGHT DEAL" PUBLIC OFFERING OF COMMON SHARES INCLUDING FULL EXERCISE OF OVER-ALLOTMENT OPTION

Osisko Development Corp. has completed its previously announced prospectus offering of common shares of the company. The offering was completed on a bought deal basis, pursuant to an underwriting agreement dated Jan. 27, 2026, among the company and a syndicate of underwriters comprising National Bank Capital Markets, RBC Capital Markets and Cantor, as co-lead underwriters and co-bookrunners, and BMO Capital Markets. Pursuant to the offering, the company issued an aggregate of 40,607,650 common shares at a price of $3.54 (U.S.) per common share for aggregate gross proceeds of $143,751,081 (U.S.), including the exercise in full by the underwriters of their overallotment option.

"We see 2026 as a key inflection point for Osisko Development and our flagship, fully permitted Cariboo gold project. Proceeds from this offering unlock our ability to accelerate infill conversion drilling aimed at upgrading existing mineral resources to mineral reserves, potentially setting the stage for a more meaningful annual gold production profile, subject to evaluation of throughput expansion scenarios. Importantly, this work can advance in parallel with, and independent of, our ongoing preconstruction activities and onwards as we progress towards a final investment decision on the base case outlined in the 2025 feasibility study. This is a unique opportunity to potentially enhance project value by converting additional reserve ounces into the mine plan located near or within planned infrastructure, potentially delivering near-term benefits for shareholders," stated Sean Roosen, chairman and chief executive officer.

The company intends to use the net proceeds of the offering to finance infill conversion drilling and at depth exploration at the Cariboo gold project and for general working capital purposes, as further described in the Canadian prospectus supplement and the United States prospectus supplement (each as defined below).

In connection with the offering, the underwriters were paid a cash commission equal to 4.5 per cent of the aggregate gross proceeds of the offering.

The offering was completed in Canada by way of a prospectus supplement dated Jan. 27, 2026, to the short form base shelf prospectus of the company dated Dec. 23, 2025, in each of the provinces and territories of Canada, and was completed in the United States by way of a prospectus supplement to the base shelf prospectus contained in the company's effective registration statement on Form F-10 (file No. 333-292328), which U.S. Prospectus Supplement was filed by the company with the U.S. Securities and Exchange Commission (the SEC). Copies of the base shelf prospectus, the Canadian prospectus supplement and the documents incorporated by reference therein are accessible under the company's profile on SEDAR+. Copies of the registration statement (including the base shelf prospectus and the U.S. prospectus supplement) are accessible on the company's profile on EDGAR on the SEC website.

Insider participation

Double Zero Capital LP, which is an insider of the company, purchased an aggregate of 8.08 million common shares at a price of $3.54 (U.S.) for gross proceeds of $28,603,200 (U.S.), pursuant to the exercise of its pre-emptive rights in respect of the offering under the investor rights agreement dated Aug. 15, 2025, between Double Zero and the company. The Double Zero purchase is considered to be a related party transaction for the purposes of Multilateral Instrument 61-101 -- Protection of Minority Security Holders in Special Transactions. 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 purchase 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 per cent 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 per cent of the company's market capitalization.

The offering is subject to the final approval of the TSX Venture Exchange.

About Osisko Development Corp.

Osisko Development is a continental North American gold development company focused on past-producing mining camps with district-scale potential. The company's objective is to become an intermediate gold producer through the development of its flagship, fully permitted, 100-per-cent-owned Cariboo gold project, located in central British Columbia, Canada. Its project pipeline is complemented by the Tintic project located in the historic East Tintic mining district in Utah, United States, a brownfield property with significant exploration potential, extensive historical mining data and access to established infrastructure. Osisko Development is focused on developing long-life mining assets in mining-friendly jurisdictions while maintaining a disciplined approach to capital allocation, development risk management and mineral inventory growth.

We seek Safe Harbor.