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Osisko Development Intersects 164.92 g/t Gold over 10.50 meters at Cariboo Gold Project, Valley Zone

Drill Results

Osisko Development Intersects 164.92 g/t Gold over 10.50 meters at

Cariboo Gold Project, Valley Zone

MONTREAL, June 1, 2022 – Osisko Development Corp. (“Osisko Development” or the “ Company”)

(ODV TSX.V & NYSE) is pleased to announce the remaining and final drilling results from the 2021

exploration and category conversion drill campaign at the Valley Zone of its Cariboo Gold Project

(“Cariboo”) in central British Columbia.

Summary

• A total of A total of 49,500 meters were drilled in 114 holes at the Valley Zone in 2021.

• Results released below are from holes CM-21-094 to CM-21-112 (see Figures 1 and 2 for the drill

hole location maps).

• Highlights include 164.92 g/t Au over 10.50 m in hole CM-21-097 at a depth of 200 meters from

surface with high grade samples of 67.10 g/t Au over 0.50 m, 18.60 g/t Au over 0.60 m, 16.35 g/t

Au over 1.00 m, 8.15 g/t Au over 1.00 m, 1,605 g/t Au over 1.00 m ( with visible gold observed),

13.25 g/t Au over 1.00 m and 20.30 g/t Au over 1.00 m (see Figure 3 cross section).

• CM-21-099 intersected a vein corridor that assayed 15.26 g/t Au over 14.40 m and included high

grade samples of 104.5 g/t Au over 1.00 m and 61.10 g/t Au over 1.00 m.

• The drill results confirmed anomalous gold values within multiple modelled vein corridors as shown

in the cross section below. Additional noteworthy highlights are listed below.

• Detailed drilling results and a drill hole location plan map are presented at the end of this release.

Assay Highlights

• 9.26 g/t Au over 6.15 meters in hole CM-21-094 including

• 99.20 g/t Au over 0.50 meter

• 16.74 g/t Au over 3.00 meters in hole CM-21-094 including

• 29.50 g/t Au over 0.75 meter

• 5.66 g/t Au over 12.60 meters in hole CM-21-094

• 10.82 g/t Au over 7.20 meters in hole CM-21-094

• 81.50 g/t Au over 0.50 meter in hole CM-21-095

• 16.19 g/t Au over 6.70 meters in hole CM-21-095 including

• 54.90 g/t Au over 0.95 meter in hole CM-21-095

• 284.00 g/t Au over 0.50 meter in hole CM-21-096

• 7.25 g/t Au over 6.35 meters in hole CM-21-097

• 164.92 g/t Au over 10.50 meters in hole CM-21-097 including

• 1,605.00 g/t Au over 1.00 meter

• 18.99 g/t Au over 3.85 meters in hole CM-21-097 including

• 44.10 g/t Au over 1.20 meters

• 104.50 g/t Au over 0.95 meter in hole CM-21-099

• 15.26 g/t Au over 14.40 meters in hole CM-21-099 including

• 104.50 g/t Au over 1.00 meter in hole CM-21-099 and

• 61.10 g/t Au over 1.00 meter in hole CM-21-099

• 104.50 g/t Au over 0.80 meter in hole CM-21-099

• 20.71 g/t Au over 7.60 meters in hole CM-21-100

• 12.18 g/t Au over 11.85 meters in hole CM-21-100

• 6.48 g/t Au over 10.50 meters in hole CM-21-104

• 8.44 g/t Au over 6.80 meters in hole CM-21-106

• 24.55 g/t Au over 7.85 meters in hole CM-21-106 including

• 332.00 g/t Au over 0.50 meter in hole CM-21-106

• 7.93 g/t Au over 12.40 meters in hole CM-21-106 including

• 84.40 g/t Au over 0.70 meter in hole CM-21-106

• 14.14 g/t Au over 4.10 meters in hole CM-21-107

• 15.68 g/t Au over 4.20 meters in hole CM-21-107

• 6.59 g/t Au over 8.20 meters in hole CM-21-107

• 10.15 g/t Au over 10.85 meters in hole CM-21-109

Sean Roosen, CEO of Osisko Development commented,

“We are excited and encouraged by the final results received at the Valley Zone of the Cariboo Gold Project.

The Valley Zone is one of seven important mineralized zones within the broader Cariboo Gold Project, and

the Valley Zone contains 536,000 ounces of gold (4.4 million tonnes grading 3.8 g/t Au) in the indicated

category and 235,000 ounces of gold (2.1 million tonnes grading 3.4 g/t Au) in the inferred category. The

updated Mineral Resource Estimate has an effective date of May 17, 2022 and published in the recent

Preliminary Economic Assessment filed on SEDAR on May 24th, 2022. The purpose of this drilling was to

expand known vein corridors and increase confidence to support further technical work , and the goal was

successfully achieved.”

Vein corridors are defined as high- density network s of mineralized quartz veins within the axis of the

deposit’s last folding event . These mineralized structures are predominantly hosted within a brittle meta-

sandstone or calcareous meta- sandstone. Vein corridors are modelled at a minimum thickness of

2.00 meters and average a pproximately 4.50 meters true width. Individual mineralized veins within these

corridors have widths varying from centimeters to several meters and strike lengths from a few meters to

over 50 meters. These corridors have been defined from surface to a vertical depth averaging 300 meters

and remain open for expansion at depth and along strike. Gold grades are intimately associated with quartz

vein-hosted pyrite as well as pyritic, intensely silicified wall rock vein selvages.

True widths are estimated to be 60% to 75 % 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 and drill hole locations are listed in Table 2.

Figure 1: Cariboo Gold Project areas overview map (mineralized zones are shown in red)

Figure 2: Valley Zone select drilling highlights

Figure 3: Cross Section of CM-21-097

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 in Wells, BC. 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. The QAQC program was designed and approved by Lynda

Bloom, P.Geo. of Analytical Solutions Ltd.

Drill core samples are submitted to ALS Geochemistry’s analytical facility in North Vancouver, British

Columbia for preparation and analysis. The ALS facility is accredited to the ISO/IEC 17025 standard for

gold assays and all analytical methods include quality control materials at set frequencies with established

data acceptance criteria. The entire sample is crushed, and 250 grams is pulverized. Analysis for gold is

by 50g fire assay fusion with atomic absorption (“AAS”) finish with a lower limit of 0.01 ppm and upper limit

of 100 ppm. Samples with gold assays greater than 100 ppm are re-analyzed using a 1,000g screen metallic

fire assay. A selected number of samples are also analyzed using a 48 multi -elemental geochemical

package by a 4- acid digestion, followed by Inductively Coupled Plasma Atomic Emission Spectroscopy

(“ICP-AES”) and Inductively Coupled Plasma Mass Spectroscopy (“ICP-MS”).

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, Canada, is Osisko Development's flagship asset. The considerable exploration potential at depth

and along strike distinguishes the Cariboo Gold Project relative to other development assets. Osisko

Development's project pipeline is complemented by its interest in the San Antonio gold project, located in

Sonora, Mexico and the Trixie gold test mine, located in Utah, USA..

For further information, please contact Osisko Development Corp.:

Jean Francois Lemonde

VP, Investor Relations

[email protected]

Tel: 514-299-4926

Forward-looking Statements

Certain statements contained in this press release may be deemed “forward-looking statements”

within the meaning of the United States Private Securities Litigation Reform Act of 1995 and

“forward-looking information” within the meaning of applicable Canadian securities legislation.

These forward‐ looking statements, by their nature, require Osisko Development to make certain

assumptions and necessarily involve known and unknown risks and uncertainties that could

cause actual results to differ materially from those expressed or implied in these forward‐ looking

statements. Forward ‐ looking statements are not guarantees of performance. Words such as

“may”, “will”, “would”, “could”, “expect”, “believe”, “plan”, “anticipate”, “intend”, “estimate”,

“continue”, or the negative or comparable terminology, as well as terms usually used in the future

and the conditional, are intended to identify forward‐ looking statements. Information contained in

forward‐ looking statements is based upon certain material assumptions that were applied in

drawing a conclusion or making a forecast or projection, including management’s perceptions of

historical trends, current conditions and expected future developments, results of further

exploration work to define and expand mineral resources, expected conclusions of optimizat ion

studies, that vein corridors continue to be defined as a high-density network of mineralized quartz

within the axis of the last folding event and hosted within the sandstones and that the deposit

remains open for expansion at depth and down plunge, as well as other considerations that are

believed to be appropriate in the circumstances , and any other information herein that is not a

historical fact may be “forward looking information”. Material assumptions also include,

management’s perceptions of historical trends, current conditions and expected future

developments, results of further exploration work to define and expand mineral resources, as well

as other considerations that are believed to be appropriate in the circumstances. Osisko

Development considers its assumptions to be reasonable based on information currently

available, but cautions the reader that their assumptions regarding future events, many of which

are beyond the control of Osisko Development, may ultimately prove to be incorrect since they

are subject to risks and uncertainties that affect Osisko Development and its business. Such risks

and uncertainties include, among others, risks relating to capital market conditions, regulatory

framework, the ability of exploration activities (including drill results) to accurately predict

mineralization; errors in management’s geological modelling; the ability of to complete further

exploration activities, including drilling; property and stream interests in the Project; the ability of

the Company t o obtain required approvals; the results of exploration activities; risks relating to

exploration, development and mining activities; the global economic climate; metal prices; dilution;

environmental risks; and community and non-governmental actions and the responses of relevant

governments to the COVID -19 outbreak and the effectiveness of such responses. Readers are

urged to consult the disclosure provided under the heading "Risk Factors" in the Company’s

annual information form for the year ended December 31, 2021, as amended, which has been

filed on SEDAR (www.sedar.com) under the Company's issuer profile and on the U.S. Securities

Exchange Commission’s EDGAR website (www.sec.gov), for further information regarding th e

risks and other factors applicable to the exploration results. Although the Company’s believes the

expectations conveyed by the Forward-looking Statements are reasonable based on information

available at the date of preparation, no assurances can be given as to future results, levels of

activity and achievements. The Company disclaims any obligation to update any Forward-looking

Statements, whether as a result of new information, future events or results or otherwise, except

as required by law. There can be no assurance that these Forward-looking Statements will prove

to be accurate, as actual results and future events could differ materially from those anticipated

in such statements. Accordingly, readers should not place undue reliance on Forward -looking

Statements..

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in

the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of

this news release. No stock exchange, securities commission or other regulatory authority has

approved or disapproved the information contained herein.

Table 1: Cariboo Gold Project 2021 Length Weighted Drill Hole Gold Composites

HOLE ID FROM (M) TO (M) LENGTH (M) AU (G/T)

CM-21-094 67.50 73.65 6.15 9.26

Including 67.50 68.00 0.50 99.20

80.85 81.35 0.50 5.43

106.40 109.40 3.00 16.74

Including 107.30 108.05 0.75 29.50

and 108.65 109.40 0.75 25.40

121.40 121.90 0.50 7.81

127.00 131.30 4.30 3.22

Including 127.00 127.50 0.50 8.01

and 130.80 131.30 0.50 9.94

133.40 146.00 12.60 5.66

Including 133.90 134.40 0.50 13.30

and 137.60 138.10 0.50 10.30

and 141.90 142.60 0.70 13.15

and 143.20 144.70 1.50 23.30

148.80 149.45 0.65 7.64

161.85 162.35 0.50 19.10

170.70 175.05 4.35 4.21

Including 171.70 172.20 0.50 11.05

and 173.95 174.45 0.50 16.85

377.85 378.35 0.50 6.04

383.10 384.35 1.25 8.17

390.90 398.10 7.20 10.82

Including 392.25 393.75 1.50 17.35

and 393.75 394.50 0.75 16.70

and 395.85 397.10 1.25 25.50

416.70 417.20 0.50 4.73

441.15 445.80 4.65 7.30

Including 442.00 443.00 1.00 8.04

and 444.30 445.80 1.50 13.80

452.80 456.75 3.95 9.08

Including 455.30 456.25 0.95 28.60

CM-21-095 96.00 96.50 0.50 3.53

147.20 148.35 1.15 9.05

242.75 244.00 1.25 11.55

300.90 303.10 2.20 9.36

Including 300.90 301.60 0.70 17.15

and 302.60 303.10 0.50 15.30

309.95 310.80 0.85 3.26

350.35 350.85 0.50 11.85

361.50 362.00 0.50 81.50

400.00 400.75 0.75 6.62

454.50 455.00 0.50 7.69

495.30 502.00 6.70 16.19

Including 496.00 496.95 0.95 54.90

and 496.95 498.10 1.15 22.40

and 498.10 498.80 0.70 25.60