OSISKO FILES TECHNICAL REPORT FOR WINDFALL MINERAL RESOURCE ESTIMATE UPDATE

(Toronto, September 14, 2022) Osisko Mining Inc. (OSK:TSX, “Osisko” or the “Corporation”) is pleased to announce that it has filed a technical report in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101“) to update the mineral resource estimate on its 100% owned Windfall gold deposit. The technical report entitled “ Mineral Resource Estimate Update for the Windfall Project, Eeyou Istchee James Bay, Québec, Canada” and dated September 14, 2022 (with an effective date of June 7, 2022) has been prepared for Osisko by BBA Inc. The technical report is available on SEDAR (www.sedar.com) under Osisko’s issuer profile.

The technical report contains a non-material change from the news release published on August 30, 2022. Sensitivity Table 1 has been corrected for the 2.5g/t cut-off grade. This change does not impact the results of the August 30, 2022 news release as the modification affects only numbers presented for reference purposes in the news release.  The NI 43-101 Technical Report cut-off grade has been determined with reference to a 3.5g/t cut-off grade.  The Table 1 below (which is included in the Technical Report) should replace the Table 1 from the August 30, 2022 news release.

Table 1: Windfall Gold Deposit Mineral Resource Estimate Sensitivity Table

Notes:  ¹Values are rounded to nearest thousand which may cause apparent discrepancies.  ²MRE cut-off: 3.5 g/t Au. ³The cut-off grade variation is not applicable to the material in the Stockpiles.

Qualified Person

The technical report entitled, “Mineral Resource Estimate Update for the Windfall Project, Eeyou Istchee James Bay, Québec, Canada” and dated September 14, 2022 with an effective date of June 7, 2022, was prepared for Osisko by BBA Inc. (Pierre-Luc Richard, M.Sc., P.Geo (OGQ#1119) and Mathieu Belisle, P. Eng. (OIQ#128549)). Mr. Richard is an employee of PLR Resources Inc., subcontracted by BBA Inc.  for purposes of the technical report and Mr. Belisle is an employee of BBA Inc. Each of Pierre-Luc Richard and Mathieu Belisle is considered to be “independent” of Osisko for purposes of Section 1.5 of NI 43-101. The scientific and technical content in this news release has been reviewed and approved by Mr. Mathieu Savard, P.Geo (OGQ #510), President of Osisko, who is a “qualified person” (within the meaning of NI 43-101).

About Osisko Mining Inc.

Osisko is a mineral exploration company focused on the acquisition, exploration, and development of precious metal resource properties in Canada. Osisko holds a 100% interest in the high-grade Windfall gold deposit located between Val-d’Or and Chibougamau in Québec and holds a 100% undivided interest in a large area of claims in the surrounding Urban Barry area and nearby Quévillon area (over 2,400 square kilometres).

 Cautionary Statements Regarding Mineral Resource Estimate

Readers are cautioned that mineral resources are not mineral reserves and that the economic viability of mineral resources that are not mineral reserves has not been demonstrated. The mineral resource estimate described in this news release may be materially affected by geology, environmental, permitting, legal, title, socio-political, marketing or other relevant issues. The mineral resource estimate is classified in accordance with the Canadian Institute of Mining, Metallurgy and Petroleum’s “CIM Definition Standards on Mineral Resources and Mineral Reserves” incorporated by reference into NI 43-101. Readers are cautioned not to assume that further work on the stated mineral resources will lead to mineral reserves that can be mined economically.

CONTACT INFORMATION:

John Burzynski
President & Chief Executive Officer
Telephone (416) 363-8653