Drilling Intersects Wide High-Grade at Osisko’s Windfall

TORONTO, Jan. 18, 2022 - Osisko Mining Inc. (OSK:TSX. "Osisko" or the "Corporation") is pleased to provide new analytical results from the ongoing drill program at its 100% owned Windfall gold project located in the Abitibi greenstone belt, Urban Township, Eeyou Istchee James Bay, Qu?bec.

Significant new analytical results that have not been included in the recently released mineral resource estimate ("MRE") (see Osisko news release dated January 10, 2022) are presented below, and include 94 intercepts in 28 drill holes (9 from surface, 19 from underground) and 25 wedges. The infill intercepts are located inside defined January 2022 MRE blocks. The expansion intercepts are located outside the January 2022 MRE blocks and either expand MRE wireframes or are in a defined zone or corridor but do not yet correlate to a specific MRE wireframe.

Osisko Chief Executive Officer John Burzynski commented: "Today's results serve as a reminder that Windfall continues to grow in size, underscored by some of these new wide high-grade hits as the deposit opens up in the heart of the Lynx system. By virtue of the current resource, Windfall is the largest high-grade million ounce plus deposit ever discovered in Qu?bec, and it has been steadily moving up the global list of top high-grade underground gold deposits. There is nothing quite like Windfall in Canada, or even globally."

Selected high-grade intercepts include: 482 g/t Au over 5.7 metres and 380 g/t Au over 3.2 metres in OSK-W-21-1432-W10; 77.6 g/t Au over 17.3 metres in OSK-W-21-1949-W14; 124 g/t Au over 8.0 metres in OSK-W-21-2587-W2; 45.8 g/t Au over 11.0 metres and 143 g/t Au over 3.4 metres in WST-21-0707; 87.9 g/t Au over 3.2 metres in OSK-W-21-2465-W5; 83.0 g/t Au over 3.0 metres in WST-21-0895A, 37.0 g/t Au over 6.4 metres in OSK-W-21-2613 and 28.1 g/t Au over 6.0 metres in OSK-W-21-2644. Maps showing hole locations and full analytical results are available at www.osiskomining.com.

Infill Drilling

Notes: True widths are estimated at 55 - 80% of the reported core length interval. See "Quality Control and Reporting Protocols" below. CAE and CA2 = Caribou, LX4 = Lynx 4, LHW = Lynx Hanging Wall, LXM = Lynx Main, LSW = Lynx Southwest, TLX = Triple Lynx, UDD = Underdog, WNF = Windfall North, F11 = F11 Zone, and Z27 = Zone 27.

Expansion Drilling

Notes: True widths are estimated at 55 - 80% of the reported core length interval. See "Quality Control and Reporting Protocols" below. LSW = Lynx Southwest, LXM = Lynx Main, LX4 = Lynx 4, TLX = Triple Lynx, UDD = Underdog.

Drill hole location

Caribou Zone
Mineralization most commonly occurs in gold-bearing pyrite stockworks as well as semi-massive pyrite replacement zones associated with phyllic alteration (sericite-pyrite ? silica) with sulphides, pyrite dominated with minor chalcopyrite and sphalerite ranging from trace to up to 20%, and local visible gold. Mineralization is hosted in rhyolites or mafic-intermediate volcanics frequently at or near faults or the contact with felsic porphyritic intrusions.

Lynx Zone
Mineralization occurs as grey to translucent quartz-carbonate-pyrite-tourmaline veins and pyrite replacement zones and stockworks. Vein-type mineralization is associated with haloes of pervasive sericite-pyrite ? silica alteration and contain sulphides (predominantly pyrite with minor amounts of chalcopyrite, sphalerite, galena, arsenopyrite, and pyrrhotite) and local visible gold. Replacement mineralization is associated with strong pervasive silica-sericite-ankerite ? tourmaline alteration and contains disseminated pyrite from trace to 80% with local visible gold. Pyrite stockworks can form envelopes that reach several tens of metres thick. Fuchsite alteration is common and is spatially constrained to near the gabbros. Mineralization occurs at or near geological contacts between felsic porphyritic or fragmental intrusions and the host rhyolites or gabbros and locally can be hosted along the gabbro-rhyolite contact.

Underdog
Mineralization most commonly occurs in gold-bearing quartz-pyrite (? tourmaline) veins and as disseminated, stringer, semi-massive to massive pyrite with minor sphalerite, chalcopyrite and molybdenite associated with strong sericite and silica alteration. Mineralization is hosted along the intrusive contacts of a three-phase composite felsic porphyritic unit which cross-cuts felsic and mafic volcanic sequences.

Windfall North
Mineralization is hosted in sheared andesites and most commonly occurs in gold-bearing quartz veins with trace to 10% pyrite, traces of sphalerite and chalcopyrite, and local visible gold. Mineralization is hosted in a silica-carbonate-sericite alteration envelope and is constrained within shear zones with pervasive sericite-carbonate ? fuchsite ? silica alteration.

Zone 27
Mineralization most commonly occurs as replacement-type characterized by 5% to 50% disseminated, stringer, semi-massive or stockwork pyrite, ptygmatic tourmaline veins, quartz-tourmaline crustiform veins, local quartz-carbonate veins, and local visible gold. Mineralization is associated with moderate to strong sericite, weak to strong silica, weak chlorite and carbonate and locally weak fuchsite and is hosted in strongly altered andesites, in or at the contact of the rhyolite, or along the contacts with felsic porphyritic intrusions.

F-Zones
Mineralization is hosted in sheared andesites with carbonate replacement or quartz veining and occurs as quartz ? ankerite veinlets or as replacement type in shear zones and is characterised by trace to 10% pyrite with local visible gold. Alteration is dominated by sericite-fuchsite-tourmaline-pyrite.

Qualified Person
The scientific and technical content of this news release has been reviewed, prepared and approved by Mr. Louis Grenier, M.Sc.A., P.Geo. (OGQ 800), Director of Exploration for Osisko's Windfall gold project, who is a "qualified person" as defined by National Instrument 43-101 - Standards of Disclosure for Mineral Projects ("NI 43-101").

Quality Control and Reporting Protocols
True width determination is estimated at 55-80% of the reported core length interval for the zone. Assays are uncut except where indicated. Intercepts occur within geological confines of major zones but have not been correlated to individual vein domains at this time. Reported intervals include minimum weighted averages of 3.5 g/t Au diluted over core lengths of at least 2.0 metres. NQ core assays were obtained by either 1-kilogram screen fire assay or standard 50-gram fire-assaying-AA finish or gravimetric finish at (i) ALS Laboratories in Val d'Or, Qu?bec, Vancouver, British Colombia, Lima, Peru or Vientiane, Laos (ii) Bureau Veritas in Timmins, Ontario. 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. Approximately 5% of sample pulps are sent to secondary laboratories for check assay.

About the Windfall Gold Deposit
The Windfall gold deposit is located between Val-d'Or and Chibougamau in the Abitibi region of Qu?bec, Canada. The Mineral Resource Estimate ("MRE") defined by Osisko, as disclosed in the news release dated January 10, 2022 and assuming a cut-off grade of 3.50 g/t Au, comprises 565,000 tonnes at 11.6 g/t Au (210,000 ounces) in the measured mineral resource category, 8,907,000 tonnes at 10.5 g/t Au (2,994,000 ounces) in the indicated mineral resource category and 13,035,000 tonnes at 8.6 g/t Au (3,585,000 ounces) in the inferred mineral resource category. The key assumptions, parameters and methods used to estimate the mineral resource estimate disclosed in the January 10, 2022 news release, certain of which are described in the January 10, 2022 news release, will be further described in the full technical report being prepared for this updated mineral resource estimate in accordance with NI 43-101, and will be available on SEDAR (www.sedar.com) under the Corporation's issuer profile within 45 days from January 10, 2022. The Windfall gold deposit is currently one of the highest-grade resource-stage gold projects in Canada and has world-class scale. Mineralization occurs in three principal zones: Lynx, Main Zone, and Underdog. Mineralization is generally comprised of sub-vertical zones following intrusive porphyry contacts plunging to the northeast. The resources are defined from surface to a depth of 1,600 metres as it now includes the Triple 8 (T8) zone. The resources excluding T8 are defined from surface to a depth of 1,200 metres. The deposit remains open along strike and at depth. Mineralization has been identified at surface in some areas and as deep as 2,625 metres in others with significant potential to extend mineralization down-plunge and at depth.

About Osisko Mining Inc.
Osisko is a mineral exploration company focused on the acquisition, exploration, and development of gold resource properties in Canada. Osisko holds a 100% interest in the high-grade Windfall gold deposit located between Val-d'Or and Chibougamau in Qu?bec and holds a 100% undivided interest in a large area of claims in the surrounding Urban Barry area and nearby Qu?villon area (over 2,600 square kilometres).

Cautionary Note Regarding Forward-Looking Information
This news release contains "forward-looking information" within the meaning of the applicable Canadian securities legislation that is based on expectations, estimates, projections and interpretations as at the date of this news release. Any statement that involves predictions, expectations, interpretations, beliefs, plans, projections, objectives, assumptions, future events or performance (often, but not always, using phrases such as "expects", or "does not expect", "is expected", "interpreted", "management's view", "anticipates" or "does not anticipate", "plans", "budget", "scheduled", "forecasts", "estimates", "potential", "feasibility", "believes" or "intends" or variations of such words and phrases or stating that certain actions, events or results "may" or "could", "would", "might" or "will" be taken to occur or be achieved) are not statements of historical fact and may be forward-looking information and are intended to identify forward-looking information. 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 key assumptions, parameters and methods used to estimate the mineral resource estimate disclosed in this news release; the prospects, if any, of the Windfall gold deposit; timing and ability of Osisko to file a technical report for the mineral resource estimate disclosed in this news release; the timing and ability of Osisko, if at all, to publish a feasibility study for the Windfall gold deposit; the amount and type of drilling to be completed and the timing to complete such drilling; the focus of the remaining infill drilling; the trend of grade increase; the Lynx zone remaining open to expansion down plunge; upgrading a inferred mineral resource to a measured mineral resource or indicated mineral resource category; future drilling at the Windfall gold deposit; the significance of historic exploration activities and results. Such factors include, among others, risks relating to the ability of exploration activities (including drill results) to accurately predict mineralization; errors in management's geological modelling; the ability of Osisko to complete further exploration activities, including (infill) drilling; property and royalty interests in the Windfall gold deposit; the ability of the Corporation to obtain required approvals; the results of exploration activities; risks relating to mining activities; the global economic climate; metal prices; dilution; environmental risks; and community and non-governmental actions. Although the forward-looking information contained in this news release is based upon what management believes, or believed at the time, to be reasonable assumptions, Osisko cannot assure shareholders and prospective purchasers of securities of the Corporation that actual results will be consistent with such forward-looking information, as there may be other factors that cause results not to be as anticipated, estimated or intended, and neither Osisko nor any other person assumes responsibility for the accuracy and completeness of any such forward-looking information. Osisko does not undertake, and assumes no obligation, to update or revise any such forward-looking statements or forward-looking information contained herein to reflect new events or circumstances, except as may be required by law.

CONTACT INFORMATION:
John Burzynski
Chief Executive Officer
Telephone (416) 363-8653