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Osisko Development Files Technical Report ON Initial Mineral Resource Estimate FOR Trixie, Tintic Project

Resource Estimates Technical Reports (NI 43-101)

NYSE: ODV TSXV: ODV NEWS RELEASE

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OSISKO DEVELOPMENT FILES TECHNICAL REPORT ON INITIAL MINERAL

RESOURCE ESTIMATE FOR TRIXIE, TINTIC PROJECT

Montreal, Québec, January 31, 2023 – Osisko Development Corp. (NYSE: ODV, TSXV: ODV) ("Osisko

Development" or the "Company") announces the filing of a technical report (the "Technical Report") in

relation to the initial mineral resource estimate ("MRE") for the Company's 100%-owned underground Trixie

deposit ("Trixie") (the "Trixie MRE"), within the Company's wider Tintic Projec t ("Tintic" or the " Tintic

Project"), located in central Utah, U.S.A. Highlights from the previously-announced Trixie MRE disclosed

in the Company's news release dated January 17, 2023 are presented below, and are consistent with the

Technical Report.

The Technical Report, titled " NI 43-101 Technical Report, Initial Mineral Resource Estimate for the Trixie

Deposit, Tintic Project, Utah, United States of America" and dated January 27, 2023 (with an effective date

of January 10, 2023), was prepared and compiled for the Company by independent representatives of

Micon International Limited in accordance with National Instrument 43 -101 – Standards of Disclosure for

Mineral Projects ("NI 43 -101"), and is available on SEDAR (www.sedar.com) and on EDGAR

(www.sec.gov) under Osisko Development's issuer profile and on the Company's website at

https://osiskodev.com/tintic-project.

TRIXIE MINERAL RESOURCE ESTIMATE

Table 1: 2023 Trixie Mineral Resource Estimate (all zones) – January 10, 2023

Classification Tonnes

(000's)

Au Grade

(g/t)

Contained

Gold

(000's oz)

Ag Grade

(g/t)

Contained

Silver

(000's oz)

Measured 11 190.61 67 195.53 69

Indicated 225 20.17 146 43.73 316

Measured and Indicated 236 28.08 213 50.77 385

Inferred 385 19.64 243 42.82 530

Notes (applicable to Tables 1, 2, and 3)

1. Troy ounces ("oz"), gold ("Au"), silver ("Ag"), tonnes ("t"), grams per tonne ("g/t").

2. Effective date of the Trixie MRE is January 10, 2023.

3. Each of Mr. William Lewis P.Geo, of Micon International Limited and Alan S J San Martin , AusIMM(CP), of Micon International

Limited (i) has reviewed and validated the Trixie MRE, (ii) is considered to be independent of the Company for purposes of

Section 1.5 of NI 43-101, and (iii) is a "qualified person" for purposes of NI 43-101.

4. The Trixie MRE is comprised of five zones within the greater T rixie area: T1, T2, T3, T4 and 75 -85. No blocks in the T3 meet

the cut-off grade used for the Trixie MRE.

5. The Trixie MRE disclosed in this news release were estimated using the CIM standards on mineral resources and reserves

definitions, and guidelines prepared by the CIM standing committee on reserve definitions and adopted by the CIM council.

6. Mineral Resources are reported when they are within potentially mineable shapes derived from a stope optimizer algorithm,

assuming an underground longhole stoping mining method with stopes of 6.1 m x 6.1 m x minimum 1.5 m dimensions.

7. Mineral resources are not mineral reserves and do not have demonstrated economic viability.

8. Geologic modelling was completed by Osisko Development 's senior production geologist Courtney Kurtz, P.G. of Utah, USA

using Leapfrog Geo software. The Trixie MRE was completed by Osisko Development 's Chief Resource Geologist, Daniel

Downton, P.Geo. using Datamine Studio RM Pro 1.12 software . The Trixie MRE was reviewed and verified by William Lewis

and Alan San Martin of Micon International Ltd.

9. The estimate is reported for an underground mining scenario and with USD assumptions. The cut -off grade of 4.85 g/t Au was

calculated using a gold price of US $1,750 per ounce, a CAD:USD exchange rate of 1.3 0; total mining, processing and G&A

costs of US$226.62 per imperial ton a combined royalty of 4.5% and an average metallurgical recovery of 95%.

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10. Average bulk density values in the mineralized domains were assigned to the T1 (2.616 T/m3), T2 (2.955 T/m3), T3 (2.638 T/m3),

T4 (2.621 T/m3), and 75-85 (2.617 T/m3) domains.

11. Inverse Distance Squared interpolation method was used with a parent block size of 1.2 m x 1.2 m x 1.8 m.

12. The results of the Trixie MRE are presented in-situ. Calculations used metric units (metres, tonnes, g/t). The number of tonnes

is rounded to the nearest thousand. Any discrepancies in the totals are due to rounding effects.

13. Neither the Company nor Micon Internation al Limited is aware of any known environmental, permitting, legal, title -related,

taxation, socio-political, marketing or other relevant issue that could materially affect the mineral resource estimate other than

disclosed in this news release.

Table 2: 2023 Trixie MRE Separated by Domain – January 10, 2023

Domain Category Tonnes Grade

(Au g/t)

Contained

Gold (oz)

Grade

(Ag g/t)

Contained

Silver (oz)

T1

Measured – – – – –

Indicated 34,470 16.39 18,159 30.55 33,856

M+I 34,470 16.39 18,159 30.55 33,856

Inferred 134,665 16.59 71,832 38.51 166,716

T2

Measured 10,938 190.61 67,029 195.53 68,757

Indicated 6,705 138.30 29,815 107.95 23,272

M+I 17,643 170.73 96,844 162.24 92,029

Inferred 25,181 101.37 82,070 146.32 118,457

T4

Measured – – – – –

Indicated 178,825 16.64 95,667 43.65 250,941

M+I 178,825 16.64 95,667 43.65 250,941

Inferred 128,038 9.10 37,460 21.64 89,063

75-85

Measured – – – – –

Indicated 4,870 14.10 2,207 51.77 8,106

M+I 4,870 14.10 2,207 51.77 8,106

Inferred 96,962 16.58 51,691 49.89 155,530

Total

Measured 10,938 190.61 67,029 195.53 68,757

Indicated 224,870 20.17 145,849 43.73 316,175

M+I 235,808 28.08 212,878 50.77 384,932

Inferred 384,845 19.64 243,053 42.82 529,766

Refer to notes described under Table 1, which are also applicable to Table 2 in their entirety.

Table 3: Trixie MRE Cut-Off Grade ("COG") Sensitivity (Base Case in Bold) – January 10, 2023

Classification Tonnes COG Grade

(Au g/t)

Contained

Gold (oz)

Grade

(Ag g/t)

Contained

Silver (oz)

Measured +

Indicated

334,672 2.50 20.83 224,173 42.82 460,779

307,608 3.00 22.42 221,774 44.89 443,994

282,778 3.50 24.10 219,084 46.57 423,392

262,447 4.00 25.68 216,661 48.36 408,078

246,598 4.50 27.05 214,455 49.84 395,124

235,808 4.85 28.08 212,878 50.77 384,932

233,051 5.00 28.35 212,436 51.15 383,279

219,345 5.50 29.79 210,054 52.66 371,399

209,391 6.00 30.92 208,184 53.92 363,007

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Classification Tonnes COG Grade

(Au g/t)

Contained

Gold (oz)

Grade

(Ag g/t)

Contained

Silver (oz)

198,274 6.50 32.30 205,914 55.54 354,071

189,341 7.00 33.50 203,919 56.92 346,468

181,989 7.50 34.55 202,159 57.85 338,499

Inferred

553,279 2.50 14.75 262,371 38.22 679,912

493,696 3.00 16.19 256,945 39.98 634,610

450,545 3.50 17.42 252,276 41.35 598,941

420,273 4.00 18.37 248,242 42.24 570,717

397,456 4.50 19.18 245,047 42.52 543,387

384,845 4.85 19.64 243,053 42.82 529,766

379,046 5.00 19.87 242,188 43.02 524,210

361,726 5.50 20.56 239,154 43.98 511,444

347,256 6.00 21.18 236,435 44.95 501,843

329,274 6.50 21.97 232,593 46.19 488,985

313,378 7.00 22.74 229,161 47.45 478,092

296,008 7.50 23.63 224,925 48.87 465,129

Note: Micon has reviewed the COG used in the sensitivity analysis relating to the Trixie MRE and is of the opinion that the individual

cut-off grades used in the sensitivity analysis meet the test of reasonable prospects of economic extraction. Refer to notes

described under Table 1, which are also applicable to Table 3 in their entirety.

Table 4: Trixie MRE Cut-off Grade Calculation Breakdown

PARAMETERS VALUES

Mining Cost ($/ST) $60.00

G&A ($/ST) $64.97

Haulage ($/ST) $10.00

Milling ($/ST) $89.00

Total Refining Cost $2.65

Gold Price $1,750

Royalty (Combination) 4.50%

Mill Recovery 95.0%

Cut-off Grade (COG) 4.85

Qualified Persons

The scientific and technical information contained in this news release has been reviewed and approved

by Maggie Layman, P.Geo., Vice President, Exploration of Osisko Development, and a " qualified person"

("QP") within the meaning of NI 43-101.

The independent QPs for the Trixie MRE, as defined by NI 43-101, are William Lewis, P.Geo. and Alan S.

J. San Martin AusIMM(CP) of Micon International Limited. Each of the QPs is independent of Osisko

Development and has reviewed and approved the content in this news release.

Quality Assurance (QA) – Quality Control (QC)

True width determination is estimated to be approximately 0.3 m to 2.4 m (1 to 8 ft.) wide for the T2 structure

and approximately 3 m to 25 m (10 to 80 ft.) for the T4 mineralized stockwork zone located in the hanging

wall of the T2 structure. All underground face samples are collected by TCM geologists from each of the

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active mining faces, with samples transported by the geologists from Trixie to the on -site TCM laboratory

located at the Burgin administrative complex. Underground samples are dried, crushed to <10 mm and a

250 g split is taken. The split is pulverized, and a 30 g Fire Assay with gravimetric finish is completed to

determine gold and silver grades, reported in oz/short ton and g/t.

The TCM Burgin laboratory is not a certified analytical laboratory, however, the facility is managed by a

qualified Laboratory Manager with annual auditing by technical staff. Inter -laboratory check assays using

ALS Laboratory as a third-party independent analysis of samples is routinely carried out as part of ongoing

Quality Assurance-Quality Control ("QA/QC") work. Certified OREAS QC standards and blanks are inserted

at regular intervals in the sample stream to monitor laboratory performance.

All drill core and exploration samples are dispatched to ALS Laboratory for offsite sample preparation and

analysis. Samples are assigned a unique sample ID. All geological and sampling information is entered into

Datamine Fusion database. Core is sawn in half and half are sampled. Certified standards and blanks

inserted into all sample dispatches. Samples are collected by Old Dominion Transportation and dispatched

to ALS Laboratory in Reno, NV. Sample submission forms accompany the samples , and digital copies

emailed to ALS.

All sample preparation is completed by ALS, including crushing and pulverizing (Prep31) of samples.

Analytical assays include gold and silver by fire assay of 50 g sample with AAS finish (Au-AA26), over limits

by gravimetric analysis (Au-Grav22). Multi element analysis is by four acid digest (ME -MS61). The pulps

are returned to Osisko Development and coarse rejects are disposed after 90 days. Assays are reported

to Osisko Development, and then loaded into Datamine Fusion, QA/QC samples are checked, and assays

merged with sample information for future reporting.

About Osisko Development Corp.

Osisko Development Corp. is a premier North American gold development company focused on high-quality

past-producing properties located in mining friendly jurisdictions with district scale potential. The Company's

objective is to become an intermediate gold producer by advancing its 100%-owned Cariboo Gold Project,

located in central B.C., Canada, the recently acquired Tintic Project in the historic East Tintic mining district

in Utah, U.S.A., and the San Antonio Gold Project in Sonora, Mexico. In addition to considerable brownfield

exploration potential of these properties, that benefit from significant historical mining data, existing

infrastructure and access to skilled labour, the Company's project pipeline is complemented by other

prospective exploration properties. The Company's strategy is to develop attractive, long -life, socially and

environmentally sustainable mi ning assets, while minimizing exposure to development risk and growing

mineral resources.

For further information, please contact Osisko Development Corp.:

Sean Roosen Philip Rabenok

Chairman and CEO Director, Investor Relations

Email: [email protected] Email: [email protected]

Tel: +1 (514) 940-0685 Tel: +1 (437) 423-3644

CAUTIONARY STATEMENTS

Cautionary Statement Regarding Estimates of Mineral Resources

This news release uses the terms measured, indicated and inferred mineral resources as a relative measure of the level of confidence

in the resource estimate. Readers are cautioned that mineral resources are not mineral reserves and that the economic viabili ty of

resources that are not mineral reserves has not been demonstrated. The mineral resource estimate disclosed in this news release

may be materially affected by geology, environmental, permitting, legal, title, socio -political, marketing or other relevant issues. The

mineral resource estimate is classified in accordance with the Canadian Institute of Mining, Metallurgy and Petroleum's "CIM Definition

Standards on Mineral Resources and Mineral Reserves" incorporated by reference into NI 43 -101. Under NI 43 -101, estimates of

inferred mineral resources may not form the basis of feasibility or pre -feasibility studies or economic studies except for preliminary

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economic assessments. Readers are cautioned not to assume that further work on the stated resources will lead to mineral rese rves

that can be mined economically.

Cautionary Statement Regarding Test Mining Without Feasibility Study

The Company cautions that the decision to commence small-scale underground mining activities and batch vat leaching at the Trixie

test mine has been made without the benefit of a feasibility study, or reported mineral resources or mineral reserves, demonstrating

economic and technical viability, and, as a result there may be increased uncertainty of achieving any particular level of re covery of

material or the cost of such recovery. The Company cautions that historically, such projects have a much higher risk of economic and

technical failure. There is no guarantee that production will continue as anticipated or at all or that anticipated production costs will be

achieved. The failure to continue production may have a material adverse impact on the Company's ability to generate revenue and

cash flow to fund operations. Failure to achieve the anticipated production costs may have a material adverse impact on the

Company's cash flow and potential profitability. In continuing current operations at Trixie after closing, the Company will not be basing

its decision to continue such operations on a feasibility study, or reported mineral resources or mineral reserves demonstrat ing

economic and technical viability. The Company cautions that mining at Trixie could be suspended at any time.

Cautionary Statement to U.S. Investors

The Company is subject to the reporting requirements of the applicable Canadian securities laws, and as a result rep orts information

regarding mineral properties, mineralization and estimates of mineral reserves and mineral resources, including the information in the

Tintic Technical Report and this news release, in accordance with Canadian reporting requirements, which are governed by NI 43 -

101. As such, such information concerning mineral properties, mineralization and estimates of mineral reserves and mineral resources,

including the information in the Tintic Technical Report and this news release, is not comparable t o similar information made public

by U.S. companies subject to the reporting and disclosure requirements of the U.S. Securities and Exchange Commission (" SEC").

FORWARD LOOKING STATEMENTS

Certain statements contained in this news 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 t hose

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; the utility and significance of historic data, including the significance of the district h osting past

producing mines; the unique mineralization at Trixie; the potential of high grade gold mineralization on Trixie; the results (if any) of

further exploration work to define and expand mineral resources; the ability of exploration work (including drilling) to accurately predict

mineralization; the ability to generate additional drill targets; the ability of management to understand the geology and pot ential of

Trixie; the timing and ability of the Company to produce the Trixie MRE (or any subsequent MRE) (if at all); the inform ation and the

scope of the contemplated Trixie MRE (and any subsequent MRE); the impact of the Trixie MRE; the ability of the Company to

complete its exploration objectives in 2023 in the timing contemplated (if at all); the ongoing advancement of the Trix ie decline; the

deposit remaining open for expansion at depth and down plunge; the ability to realize upon any mineralization in a manner tha t is

economic; 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 perceptio ns of

historical trends, the ability of exploration (including drilling) to accurately predict mineralizatio n, budget constraints and access to

capital on terms acceptable to the Company, current conditions and expected future developments, results of further explorati on

work to define or expand any mineral resources, the ability to continue production at Trixie , 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 fut ure 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 tha t affect

Osisko Development and its business. Such risks and uncertainties include, among others, risks relating to capital market conditions

and the Company's ability to access capital on terms acceptable to the Company for the contemplated exploration and development

at Tintic; the ability to continue current operations and exploration; regulatory framework; the ability of exploration activities (including

drill results) to accurately predict mineralization; errors in management's geological modelling; the ability to expand opera tions or

complete further exploration activities, including drilling; property and stream interests in the Tintic Project; the ability of the Company

to obtain required approvals; the results of exploration activities; risks relating to exploration, development and mining ac tivities; the

global economic climate; metal price s; 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 Osisko Development's issuer profile and on the

SEC's EDGAR website (www.sec.gov), for further info rmation regarding the 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 require d by law. There can be no assurance that these forward -looking statements will

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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.