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Osisko Intersects 8.43 G/T Au over 8.40 Meters at Valley Zone Infill Drilling ON Cariboo GOLD Project

Drill Results

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OSISKO INTERSECTS 8.43 G/T AU OVER 8.40 METERS AT VALLEY ZONE INFILL

DRILLING ON CARIBOO GOLD PROJECT

MONTREAL, February 2, 2021 – Osisko Development Corp. (“Osisko” or the “Company”) (TSX.V-ODV)

is pleased to announce drilling results from the category conversion drill program campaign at the Cariboo

Gold Project (“Cariboo”) in central British Columbia.

This news release discusses the assay results from holes CM -20-064 to CM -20-084 drilled on Cow

Mountain and Valley Zone in 2020 (Figures 1 and 2). Highlights include 8.43 g/t Au over 8.40 meters in

hole CM -20-083 including a higher -grade zone of 84.5 g/t Au over 0.5 meter . Hole CM -20-083 was

extended to a depth of 538 meters and intersected consistent mineralized veins at depth. A cross sect ion

with CM -20-083 is presented in Figure 3. This mineralization is not currently within any modelled vein

corridors and extends our known vein corridors in this area by up to 50 meters. Complete assay highlights

are presented in Table 1. A total of nine r igs are currently active on the property, four of which are at the

Valley Zone deposit.

Sean Roosen, CEO of Osisko Development commented, “The most recent high -grade results from the

Valley Zone certainly go to the character of this project. We are still seeing many exciting new zones in this

project that are within the current mine plan area. With the recent financing s of over 200 million dollars

completed, we will be increasing our rig count and intensifying our exploration efforts both in the current

mine plan area and on the new targets that have been generated on along the 83km (50 mile) long

mineralized trend.”

Further highlights from drilling at Valley are presented below.

Valley Zone Drilling Highlights:

 CM-20-069: 47.6 g/t Au over 0.90 meter

 CM-20-070: 23.92 g/t Au over 1.75 meters including 59.7 g/t Au over 0.5 meter

 CM-20-070: 12.01 g/t Au over 2.75 meters including 60.2 g/t Au over 0.5 meter

 CM-20-072: 16.30 g/t Au over 2.25 meters including 28.8 g/t Au over 1.15 meters

 CM-20-072: 6.30 g/t Au over 9.15 meters

 CM-20-078: 4.18 g/t Au over 7.70 meters

 CM-20-083: 8.43 g/t Au over 8.40 meters including 84.50 g/t Au over 0.50 meter

 CM-20-083: 34.50 g/t Au over 1.10 meters

 CM-20-083: 10.88 g/t Au over 3.05 meters

Mineralized quartz veins on the Cariboo Gold Project are overall sub -vertical dip and northeast strike. Vein

corridors are defined as a high-density network of mineralized quartz veins within the axis of the F3

fold and hosted within the sandstones . Vein corridors are modelled at a minimum thickness of 2

meters and individual veins within each corridor range in width from millimeter to several meters.

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The modelled vein corridors for the resource update includes the internal dilution of the subeconomic

sandstone within these vein corridors. These corridors have been defined from surface to a vertical depth

averaging 300 meters and remain open for expansion at depth and down plunge. Gold grades are intimately

associated with vein-hosted pyrite as well as pyritic, intensely silicified wall rock haloes in close proximity to

the veins.

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, drill hole locations are listed in Table 2.

Figure 1: Cariboo Deposit Areas

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Figure 2: Valley Zone plan map of drill hole locations

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Figure 3: Drill hole Cross Section.

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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 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 app roved 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 sta ndard 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 a tomic 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 mult i-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 well-capitalized and 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

resource 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. The considerable exploration 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 second half of 2021. 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 Mexic o. Osisko Development will begin trading on the TSX Venture

Exchange under the symbol "ODV" on December 2, 2020.

For further information, please contact Osisko Development Corp.:

Jean Francois Lemonde

VP Investors Relations.

[email protected]

Forward-looking Statements

Certain statements contained in this press release may be deemed “forward‐looking statements” within the meaning of

applicable Canadian and U.S. securities laws. These forward ‐looking statements, by their nature, require Osisko 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

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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

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

the axis of the F3 fold 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. Osisko 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, may ult imately prove to be

incorrect since they are subject to risks and uncertainties that affect Osisko and its business. Such risks and

uncertainties 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 to complete further

exploration activities, including drilling; property and royalty interests in the Cariboo 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 and the

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

For additional information with respect to these and other factors and assumptions underlying the forward ‐looking

statements made in this news release concerning Osisko Development, see the Filing Statement available

electronically on SEDAR (www.sedar.com) under Osisko Development's issuer profile. The forward‐looking statements

set forth herein concerning Osisko Development reflect management's expectations as at the date of this news release

and are subject to change after such date. Osisko Development disclaims any intention or obligation to update or revise

any forward -looking statements, whether as a result of new information, future events or otherwi se, other than as

required by law.

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 2020 Length Weighted Drill Hole Gold Composites

HOLE ID FROM (M) TO (M) LENGTH

(M) AU (G/T) TARGET

CM-20-064 45.00 45.50 0.50 8.15 VALLEY ZONE

93.30 93.85 0.55 5.62

98.00 98.50 0.50 3.44

175.40 176.70 1.30 4.23

259.75 260.25 0.50 18.10

276.20 276.70 0.50 8.10

325.50 327.70 2.20 6.19

INCLUDING 327.10 327.70 0.60 19.85

332.25 332.80 0.55 3.01

CM-20-065 165.00 165.50 0.50 3.47 VALLEY ZONE

CM-20-066 153.00 155.50 2.50 8.25

INCLUDING 153.00 153.50 0.50 35.30

180.90 182.65 1.75 4.63

187.50 188.85 1.35 6.09

192.70 197.95 5.25 4.18

INCLUDING 195.95 196.95 1.00 12.50

AND 196.95 197.95 1.00 4.83

CM-20-067 20.80 21.30 0.50 3.30 VALLEY ZONE

176.70 179.35 2.65 7.11

244.30 244.80 0.50 6.17

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CM-20-068 157.20 160.15 2.95 6.29 VALLEY ZONE

INCLUDING 157.20 158.10 0.90 9.64

AND 158.10 159.15 1.05 5.54

226.20 226.70 0.50 3.67

CM-20-069 125.50 127.75 2.25 3.54 VALLEY ZONE

INCLUDING 125.50 126.00 0.50 7.19

AND 127.25 127.75 0.50 8.71

153.50 154.35 0.85 6.99

305.45 308.65 3.20 6.85

INCLUDING 305.45 306.80 1.35 12.25

AND 308.15 308.65 0.50 5.04

403.30 404.00 0.70 26.00

459.30 459.80 0.50 3.60

501.20 505.85 4.65 6.08

INCLUDING 502.00 502.50 0.50 45.80

538.35 539.25 0.90 47.60

CM-20-070 211.80 212.30 0.50 20.60 VALLEY ZONE

211.80 214.80 3.00 3.95

INCLUDING 211.80 212.30 0.50 20.60

234.75 235.70 0.95 8.02

254.70 256.45 1.75 23.92

INCLUDING 254.70 255.45 0.75 15.35

AND 255.95 256.45 0.50 59.70

271.75 274.50 2.75 12.01

INCLUDING 274.00 274.50 0.50 60.20

279.45 282.00 2.55 4.17

338.15 338.65 0.50 8.07

Cm-20-071 HOLE ABANDONED VALLEY ZONE

CM-20-072 242.40 244.00 1.60 5.94 VALLEY ZONE

INCLUDING 242.40 242.90 0.50 11.90

254.40 256.65 2.25 16.30

INCLUDING 255.50 256.65 1.15 28.80

265.05 274.20 9.15 6.30

INCLUDING 265.05 265.80 0.75 16.95

AND 265.80 267.00 1.20 5.83

AND 271.60 272.20 0.60 38.50

AND 272.20 273.70 1.50 5.76

280.85 284.05 3.20 6.01

INCLUDING 283.50 284.05 0.55 18.95

293.50 294.20 0.70 6.95

CM-20-073 HOLE ABANDONED VALLEY ZONE

CM-20-074 180.00 180.65 0.65 3.39 VALLEY ZONE

331.80 333.00 1.20 21.50

CM-20-075 33.50 35.00 1.50 8.03 VALLEY ZONE

40.10 40.60 0.50 20.30

46.00 47.00 1.00 3.62

CM-20-076 40.70 41.20 0.50 5.33

COW

MOUNTAIN

42.70 43.50 0.80 3.15

56.60 57.60 1.00 18.28

INCLUDING 57.10 57.60 0.50 23.20

152.60 154.70 2.10 6.84

INCLUDING 152.60 153.55 0.95 12.10

CM-20-077 265.70 266.80 1.10 3.85 VALLEY ZONE

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CM-20-078 20.05 20.70 0.65 11.25

COW

MOUNTAIN

60.20 64.00 3.80 5.95

INCLUDING 60.20 60.70 0.50 30.90

AND 63.00 64.00 1.00 6.32

146.60 154.30 7.70 4.18

INCLUDING 150.15 150.70 0.55 27.80

AND 152.10 152.60 0.50 5.23

167.80 168.45 0.65 3.88

177.50 181.50 4.00 4.38

INCLUDING 179.20 180.25 1.05 15.90

CM-20-079 45.30 46.00 0.70 6.28

COW

MOUNTAIN

73.00 74.50 1.50 4.14

141.00 141.85 0.85 17.30

CM-20-080 149.65 150.50 0.85 5.00 VALLEY ZONE

279.00 279.75 0.75 3.92

CM-20-081 48.75 49.25 0.50 7.09

COW

MOUNTAIN

152.20 152.80 0.60 22.80

154.30 155.30 1.00 3.87

CM-20-082 16.00 16.50 0.50 26.90

COW

MOUNTAIN

43.85 45.05 1.20 3.10

55.20 55.70 0.50 6.00

CM-20-083 144.50 145.70 1.20 12.60 VALLEY ZONE

166.30 169.00 2.70 4.30

INCLUDING 168.00 169.00 1.00 9.70

320.35 322.15 1.80 12.96

INCLUDING 321.60 322.15 0.55 38.80

330.00 338.40 8.40 8.43

INCLUDING 335.00 338.40 3.40 19.62

INCLUDING 335.00 335.50 0.50 84.50

AND 337.80 338.40 0.60 39.20

345.10 345.80 0.70 5.26

370.20 371.30 1.10 34.50

385.50 386.50 1.00 14.90

391.25 391.80 0.55 4.21

433.00 433.50 0.50 4.35

436.50 437.00 0.50 7.37

444.20 447.25 3.05 10.88

INCLUDING 445.00 446.00 1.00 20.50

AND 446.75 447.25 0.50 13.75

450.35 452.80 2.45 4.54

462.45 463.15 0.70 5.78

464.60 465.40 0.80 4.23

467.45 468.05 0.60 5.00

478.20 479.00 0.80 4.32

495.00 495.50 0.50 3.74

497.50 498.00 0.50 3.23

504.70 505.35 0.65 3.79

506.15 506.75 0.60 2.49

509.85 510.40 0.55 2.04

517.00 528.85 11.85 2.33

INCLUDING 523.00 524.00 1.00 12.00

AND 526.25 527.25 1.00 4.55