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Osisko Development Intersects 2.14 G/T Au over 21.65 Meters and 1.02 G/T Au over 39.90 Meters at Sapuchi

Drill Results

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OSISKO DEVELOPMENT INTERSECTS 2.14 G/T AU OVER 21.65 METERS AND

1.02 G/T AU OVER 39.90 METERS AT SAPUCHI

MONTREAL, November 11, 2021 – Osisko Development Corp. (“Osisko Development” or the

“Company”) (TSX.V-ODV) is pleased to announce drilling results from the 2021 exploration and category

conversion drill program campaign at its San Antonio Gold Project in Sonora State, Mexico.

Summary

• The San Antonio Gold Project is an iron oxide copper gold (“ IOCG”) style deposit with zones of

oxide, transition, and sulphides on three main target areas: Sapuchi, Golfo de Oro and California.

• A total of 27,000 meters consisting of 156 holes have been drilled thus far in 2021. The objective

of the drill program is to conduct exploration and resource drilling at a spacing of 25 meters and

historic drilling validation for the three main target areas (Figure 1).

• The first 41 holes from the Sapuchi target are presented in this news release and include SP -DD-

21-001 to SP-DD-21-060 inclusive (Figure 2).

• The Sapuchi gold mineralization is characterized by hydrothermal breccia that forms an

approximately 3,000 m long east -northeast trending mineralization corridor with i ntense sericite

and chlorite alteration in the mineralized zone. The mineralization is intrusion related within host

sedimentary rocks.

• DD-21-038 intersected 21.65 meters of oxide assaying 2.14 g/t Au, extending the oxide an

additional 15 meters at depth.

• DD-21-019 intersected 1.02 g/t Au over 39.9 0 meters in a newly discovered sulphide zone at

167.4 meters depth indicating significant exploration potential.

• Sapuchi target has a strike length of 700 meters and is open in all directions , assay highlights are

presented in the list below and shown on Figure 2.

• Detailed drilling results are presented in Table 1, drillhole locations are presented in Table 2, and

drillhole cross sections are presented in Figures 2 to 5.

Assay Highlights

• 2.16 g/t Au and 2.90 g/t Ag over 12.50 meters in hole SP-DD-21-001 including

• 11.45 g/t Au and 13.80 g/t Ag over 1.10 meters

• 2.37 g/t Au and 2.02 g/t Ag over 10.25 meters in hole SP-DD-21-006

• 1.01 g/t Au and 11.75 g/t Ag over 17.70 meters in hole SP-DD-21-006

• 1.50 g/t Au and 3.06 g/t Ag over 13.85 meters in hole SP-DD-21-007

• 1.58 g/t Au and 32.51 g/t Ag over 9.45 meters in hole SP-DD-21-007

• 1.08 g/t Au and 2.69 g/t Ag over 20.45 meters in hole SP-DD-21-008

• 1.59 g/t Au and 3.68 g/t Ag over 22.15 meters in hole SP-DD-21-008

• 2.94 g/t Au and 3.98 g/t Ag over 12.65 meters in hole SP-DD-21-008 including

• 44.40 g/t Au and 54.40 g/t Ag over 0.70 meter

• 2.24 g/t Au and 14.32 g/t Ag over 9.00 meters in hole SP-DD-21-010

• 0.72 g/t Au and 4.13 g/t Ag over 20.85 meters in hole SP-DD-21-011

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• 1.02 g/t Au and 3.90 g/t Ag over 39.90 meters in hole SP-DD-21-019

• 1.60 g/t Au and 3.09 g/t Ag over 19.30 meters in hole SP-DD-21-029

• 1.30 g/t Au and 3.06 g/t Ag over 22.00 meters in hole SP-DD-21-034

• 2.14 g/t Au and 3.05 g/t Ag over 21.65 meters in hole SP-DD-21-038

• 1.52 g/t Au and 13.77 g/t Ag over 29.20 meters in hole SP-DD-21-040

• 1.80 g/t Au and 1.19 g/t Ag over 11.85 meters in hole SP-DD-21-047

• 2.19 g/t Au and 5.35 g/t Ag over 9.10 meters in hole SP-DD-21-060

Sean Roosen, CEO of Osisko Development commented, “These initial results and geologic interpretation

from Sapuchi, give us strong confidence in the potential to build the resources significantly within the

property. With this confirmation and exploration drilling, we expect to have a resource estimation in the

following months.”

The San Antonio Gold Project gold mineralization is characterized by hydrothermal breccia that forms an

approximately 3,000 m eters long east-northeast trending mineralization corridor with the Luz del Cobre

copper deposit at the east. The gold mineralization is associated with intense sericite and chlorite alteration

and is intrusion related with host sedimentary rocks. The breccia has been defined to a vertical depth of

500 meters and at an average depth of 250 meters. The upper 250 meters of the breccia is mostly altered

and prospective. Drilling has occurred within the three major zones at Sapuchi, Golfo de Oro and California,

over a combined strike length of 900 meters of the 3000-meter trend.

True widths are estimated to be 80% to 100% of reported core length intervals. Intervals not recovered by

drilling were assigned zero grade. Top cuts have not been applied to high grade assays. Complete assay

highlights are presented in Table 1, drill hole locations are listed in Table 2.

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Figure 1: San Antonio Mineral Zones overview map

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Figure 2: Sapuchi Plan Map

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Figure 3: Sapuchi Section 632050 select drilling highlights

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Figure 4: Sapuchi Section 631950

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Figure 5: Sapuchi Section 631740

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Qualified Persons

Per National Instrument 43-101 Standards of Disclosure for Mineral Projects, Maggie Layman, P.Geo. Vice

President Exploration of Osisko Development Corp., is a Qualified Person and has prepared, validated,

and approved the technical and scientific content of this news release.

Quality Assurance – Quality Control

Once received from the drill and processed, all drill core samples are sawn in half, labelled and bagged.

The remaining drill core is subsequently stored on site at a secured facility at the project site. Numbered

security tags are applied to lab shipments for chain of custody requirements. Quality control (QC) samples

are inserted at regular intervals in the sample stream, including blanks and reference materials with all

sample shipments to monitor laboratory performance.

Drill core samples are submi tted to ALS Geochemistry and Bureau Veritas (BV) preparation laboratory in

Hermosillo and then sent to their analytical facilities in North Vancouver, British Columbia for analysis. The

facilities are accredited to the ISO/IEC 17025 standard for gold assay s and all analytical methods include

quality control materials at set frequencies with established data acceptance criteria. The entire sample is

crushed, and 200 grams is pulverized. Analytical packages for ALS and BV are AA24 and FA450

respectively. Multi Element geochemistry is also analyzed with ME MS61 at ALS and MA 200 at BV.

About Osisko Development Corp.

Osisko Development Corp. is uniquely positioned as a premier gold development company in North

America to advance the Cariboo Gold Project and other Canadian and Mexican properties, with the

objective of becoming the next mid- tier gold producer. The Cariboo Gold Project, located in central British

Columbia, is Osisko Development's flagship asset with measured and indicated resources of 21.44 Mt at

4.6 Au g/t for a total of 3.2 million ounces of gold and inferred resource of 21.69 Mt at 3.9 Au g/t for a total

of 2.7 million ounces of gold (see NI 43- 101 Technical Report and mineral resource estimate effective

October 5th, 2020) . The considerable ex ploration potential at depth and along strike distinguishes the

Cariboo Gold Project relative to other development assets as does the historically low, all-in discovery costs

of US $19 per ounce. The Cariboo Gold Project is advancing through permitting as a 4,750 tonnes per day

underground operation with a feasibility study on track for completion in the first half of 2022. Osisko

Development's project pipeline is complemented by potential near -term production targeted from the San

Antonio gold project, located in Sonora Mexico and early exploration stage properties including the Coulon

Project and James Bay Properties located in Québec as well as the Guerrero Properties located in Mexico.

Osisko Development began trading on the TSX Venture Exchange under the symbol “ ODV” on

December 2, 2020 and the Company’s 14,789,373 outstanding share purchase warrants were listed on the

TSX Venture Exchange under the symbol “ODV.WT” on October 25, 2021.

For further information, please contact Osisko Development Corp.:

Jean Francois Lemonde

VP Investor Relations

[email protected]

Tel: 514-299-4926