Osisko Mining Inc. provided an update from the ongoing drill program at its 50% owned Windfall gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Quebec. The 2023 drilling campaign primarily targeted infill areas. Since the start of the year, over 95,000 metres have been drilled by 8 underground rigs focused on the Lynx segment of the deposit.

Highlights from the 2023 drill program are presented below and include 320 intercepts from 248 drill holes and 1 edge. These highlights are intercepts with a metal factor (grams*meters) greater than 20. The intercepts are all located within the defined mineral resource estimate ("MRE") blocks as described in Osisko's feasibility study on Windfall.

The 1-kilogram screen assay method is selected by the geologist when samples contain coarse gold or present a higher percentage of pyrite than surrounding intervals. Selected samples are also analyzed for multi-elements, including silver, using a Four Acid Digestion-ICP-MS method at ALS Laboratories. Drill program design, Quality Assurance/Quality Control ("QA/QC") and interpretation of results is performed by qualified persons employing a QA/QC program consistent with NI 43-101 and industry best practices.

Standards and blanks are included with every 20 samples for QA/QC purposes by the Corporation as well as the lab. The mineral resource estimate on Windfall (with an effective date of June 7, 2022) (the "Windfall Reserve Estimate") are described in the technical report entitled "Feasibility Study for the Windfall Project, Eeyou IstChee James Bay, Quebec, Canada" (the "FS Technical Report") and dated January 10, 2023 (with an effective date of November 25, 2022). This news release contains the forward-looking information pertaining to, among other things: the Windfall gold deposit being one of the highest-grade resource-stage gold projects in Canada and having world-class scale; the expected timing (if at all) to hook-up the power line; the expected allocation of power under the power allocation agreement being realized (if any); the expected power demand for Windfall; the assumptions limitations and qualifications in the FS Technical Report, including relating to the Windfall Resource Estimate and Windfall Reserve Estimate; reliance on third-parties for infrastructure, including power lines, with reference to the agreement with Miyuukaa for the transmission of hydroelectric power to the Windfall site; the results of the FS Technical Report, including NPV, IRR, production, tax-free cash flows, capex, AISC, milling operations, average recovery, job creation; the Lynx zone remaining open to expansion down plunge.

Such factors include, among others, risks relating to the ability of the Corporation to obtain required approvals; the results of the FS technical Report, including NPV,IRR, production, tax- free cash flows, capex,AISC, milling operations,average recovery, job creation; theLynx zone remaining open to expansion up down plunge. Such factors include the ability of the Corporation to obtained required approvals; the results of its FS Technical Report, including the FS Technical Report, including the Company to obtain required approvals.