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OSISKO DEVELOPMENT REPORTS UNDERGROUND SAMPLING RESULTS AT TRIXIE, TINTIC PROJECT 154.82 g/t Au and 990.71 g/t Ag over 0.43 m in the T4 Zone

Drill Results Sampling & Geoscience Results

NYSE: ODV TSXV: ODV NEWS RELEASE

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OSISKO DEVELOPMENT REPORTS UNDERGROUND SAMPLING RESULTS

AT TRIXIE, TINTIC PROJECT

154.82 g/t Au and 990.71 g/t Ag over 0.43 m in the T4 Zone

Montreal, Québec, June 27, 2023 – Osisko Development Corp. (NYSE: ODV, TSXV: ODV) ("Osisko

Development" or the "Company") is pleased to announce underground sampling results from its ongoing

exploration program at its 100%-owned Trixie test mine ("Trixie"), within the Company's wider Tintic Project

("Tintic" or the "Tintic Project"), located in the historic East Tintic Mining District in central Utah, U.S.A.

Chris Lodder, President of Osisko Development, commented, "The underground face chip sampling at

Trixie continues to define mineralized zones , namely below the main 625 level and into the 750 level at

Trixie, and further to the south of the deposit closer to the Sioux Ajax fault within our current drill area s.

These results will assist in furthering our knowledge of the extents of the deposit and improve our targeting

in our underground exploration program at Trixie."

DRILL ASSAY HIGHLIGHTS

This news release includes assays from 444 underground exploration face, back and rib chip samples from

130 chips strings in development at Trixie (refer to Table 1). Select assay highlights include:

• 58.43 grams per tonne ("g/t") gold ("Au") and 551.10 g/t silver ("Ag") over 0.30 meters ("m")

in CH01357 (1.70 troy ounce per short ton ("oz/t") Au and 16.07 oz/t Ag over 1.00 feet ("ft.")

• 47.69 g/t Au and 214.33 g/t Ag over 0.4 6 m in CH01358 (1.39 oz/t Au and 6.25 oz/t Ag over

1.50 ft.)

• 15.36 g/t Au and 56.34 g/t Ag over 3.02 m in CH01366 (0.45 oz/t Au and 1.64 oz/t Ag over

9.90 ft.) including 37.95 g/t Au and 128.8 7 g/t Ag over 0.79 m (1.11 oz/t Au and 3.76 oz/t Ag

over 2.60 ft)

• 154.82 g/t Au and 990.71 g/t Ag over 0.43 m in CH01394 (4.52 oz/t Au and 28.90 oz/t Ag over

1.40 ft)

• 25.64 g/t Au and 138.26 g/t Ag over 0.61 m in CH01399 (0.75 oz/t Au and 4.03 oz/t Ag over

2.00 ft)

• 74.05 g/t Au and 351.18 g/t Ag over 0.15 m in CH01401 (2.16 oz/t Au and 10.24 oz/t Ag over

0.50 ft)

• 20.81 g/t Au and 558.21 g/t Ag over 0.30 m in CH01445 (0.61 oz/t Au and 16.28 oz/t Ag over

1.00 ft)

• 13.94 g/t Au and 640.46 g/t Ag over 0.30 m in CH01450 (0.41 oz/t Au and 18.68 oz/t Ag over

1.00 ft)

• 10.18 g/t Au and 300.79 g/t Ag over 0.61 m in CH01501 (0.30 oz/t Au and 8.77 oz/t Ag over

2.00 ft)

• 7.85 g/t Au and 497.81 g/t Ag over 0.91 m in CH01502 (0.23 oz/t Au and 14.52 oz/t Ag over

3.00 ft)

CHIP SAMPLE RESULTS SUMMARY

• A total of 444 underground exploration face, back and rib chip samples were collected in 130 chips

strings in development at Trixie.

• Chip samples were collected from the T2 structure and T4 stockwork on the 625 and 750 levels.

• Samples on the 750 level assayed 20.81 g/t Au and 558.21 g/t Ag over 0.30 m and additional cross

cuts are recommended for this area.

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• Sampling on the 625 level focussed on development to the south towards the Sioux Ajax fault

(Figure 2) and the majority of the sampling was within the T4 zone to avoid historical workings

intersected in late 2022.

• Samples to the south of the current Trixie Mineral Resource Estimate ("Trixie MRE") are located

in a crosscut in the T4 zone where underground diamond drilling is ongoing. Chip samples in this

area assayed 10.18 g/t Au and 300.79 g/t Ag over 0.61 m and 12.38 g/t Au and 19.34 g/t Ag over

1.22 meters. See below under the heading "About Trixie" for details of the Tintic Technical Report

(as defined herein).

• These sampling results will provide valuable data to improve our understanding and the confidence

level of the mineralized zones defined in the Trixie MRE and to support a future mineral resource

estimate update.

Face Sampling Methodology

As most structures at Trixie are steeply dipping to the east or west, current sampling procedures are

designed to sample the structure. Chip samples are collected and do not exceed 1.0 m (3 ft.) in length.

The face is washed for safety, and for better identification of mineralization, alteration and structures. The

hanging wall and footwall of the structures are marked up on the face and back, samples intervals are

marked up and follow lithological contacts.

About Trixie

The Trixie test mine is one of several gold and base metal targets within the larger Tintic Project consisting

of >17,000 acres of patented mining claims and mineral leases within the historic East Tintic Mining District

of Central Utah, U.S.A. The T2 and T4 structures at Trixie show multi -ounce gold grades associated with

high sulphidation epithermal mineralization, structurally controlled and hosted within quartzites. The T2

structure mineralization consists of native Au, and rare Au-Ag – rich telluride minerals with quartz. The T4

is a mineralized stockwork zone is located in the hanging wall of the T2 and is comprised of Au -Ag rich

mineralization in host rock quartzite with quartz-barite-sulphosalt stockwork veining. Mineralization reports

consistent multi-ounce gold grades along the entire strike length.

A 3D model and virtual site tour of Trixie and the wider Tintic Project is accessible on the Company's VRIFY

page at: https://vrify.com/decks/12801.

Information relating to the Tintic Project and the Trixie MRE is supported by the technical report titled " NI

43-101 Technical Report, Initial Mineral Resource Estimate for the Trixie Deposit, Tintic Project, Utah,

United States of America", dated January 27, 2023 (with an effective date of January 10, 2023) prepared

for the Company by independent representatives of Micon International Limited (the "Tintic Technical

Report"). Reference should be made to the full text of the Tintic Technical Report, which was prepared in

accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects ("NI 43-101")

and is available electronically on SEDAR ( www.sedar.com) and on EDGAR (www.sec.gov) under Osisko

Development's issuer profile and on the Company's website at www.osiskodev.com.

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Figure 1: Trixie Project Area

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Figure 2: Trixie Long Section

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Figure 3: Trixie Long Section Sample Highlights

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Table 1: Chip Length Weighted Assay Composites at Trixie

METRIC IMPERIAL

Hole ID Depth from

(m)

Depth to

(m) Length (m) Au (g/t) Ag (g/t) Depth

from (ft.)

Depth to

(ft.)

Length

(ft.) Au (oz/t) Ag (oz/t) Target

CH01357 0.00 0.30 0.30 58.43 551.10 0.00 1.00 1.00 1.70 16.07 T4 625

CH01358 5.21 5.67 0.46 47.69 214.33 17.10 18.60 1.50 1.39 6.25 T4 625

CH01365 2.44 2.83 0.40 5.18 11.42 8.00 9.30 1.30 0.15 0.33 T4 625

CH01366 0.85 3.87 3.02 15.36 56.34 2.80 12.70 9.90 0.45 1.64 T4 625

CH01366 Including 2.07 2.87 0.79 37.95 128.87 6.80 9.40 2.60 1.11 3.76 T4 625

CH01387 0.91 1.83 0.91 11.90 33.67 3.00 6.00 3.00 0.35 0.98 T4 625

CH01390 0.94 1.62 0.67 5.45 50.94 3.10 5.30 2.20 0.16 1.49 T4 625

CH01392 1.49 1.74 0.24 3.19 70.52 4.90 5.70 0.80 0.09 2.06 T4 625

CH01393 0.00 0.61 0.61 8.40 49.26 0.00 2.00 2.00 0.24 1.44 T4 625

CH01394 3.05 3.47 0.43 154.82 990.71 10.00 11.40 1.40 4.52 28.90 T4 625

CH01395 1.34 2.96 1.62 8.94 86.10 4.40 9.70 5.30 0.26 2.51 T4 625

CH01395 Including 1.34 2.26 0.91 12.38 125.61 4.40 7.40 3.00 0.36 3.66 T4 625

CH01398 0.00 0.85 0.85 3.98 85.12 0.00 2.80 2.80 0.12 2.48 T4 625

CH01399 0.00 1.28 1.28 14.53 76.36 0.00 4.20 4.20 0.42 2.23 T4 625

CH01399 Including 0.00 0.61 0.61 25.64 138.26 0.00 2.00 2.00 0.75 4.03 T4 625

CH01401 0.00 0.15 0.15 74.05 351.18 0.00 0.50 0.50 2.16 10.24 T4 625

CH01401 2.41 2.56 0.15 3.39 195.72 7.90 8.40 0.50 0.10 5.71 T4 625

CH01402 1.37 1.74 0.37 7.61 102.64 4.50 5.70 1.20 0.22 2.99 T2 750 L

CH01410 0.00 0.61 0.61 5.55 53.89 0.00 2.00 2.00 0.16 1.57 T2 750 L

CH01423 1.22 1.83 0.61 6.79 52.38 4.00 6.00 2.00 0.20 1.53 750 L

CH01430 0.00 0.52 0.52 18.81 53.46 0.00 1.70 1.70 0.55 1.56 T2 750 L

CH01433 0.00 0.21 0.21 8.88 8.40 0.00 0.70 0.70 0.26 0.24 T2 750 L

CH01436 0.67 0.82 0.15 11.69 56.81 2.20 2.70 0.50 0.34 1.66 T2 750 L

CH01445 0.00 0.30 0.30 20.81 558.21 0.00 1.00 1.00 0.61 16.28 T2 750 L

CH01449 0.00 0.76 0.76 1.02 127.97 0.00 2.50 2.50 0.03 3.73 T4 625

CH01449 Including 0.00 0.30 0.30 2.09 197.29 0.00 1.00 1.00 0.06 5.75 T4 625

CH01450 0.00 0.30 0.30 13.94 640.46 0.00 1.00 1.00 0.41 18.68 T2 750 L

CH01489 0.00 1.10 1.10 7.20 358.76 0.00 3.60 3.60 0.21 10.46 T2 625 L

CH01490 0.00 1.22 1.22 12.38 19.34 0.00 4.00 4.00 0.36 0.56 T2 625 L

CH01491 7.59 7.83 0.24 1.06 70.14 24.90 25.70 0.80 0.03 2.05 T2 625 L

CH01492 1.22 5.12 3.90 0.56 74.97 4.00 16.80 12.80 0.02 2.19 T2 625 L

CH01492 Including 2.50 3.72 1.22 1.06 154.17 8.20 12.20 4.00 0.03 4.50 T2 625 L

CH01501 2.44 3.05 0.61 10.18 300.79 8.00 10.00 2.00 0.30 8.77 T4 625

CH01502 3.05 3.96 0.91 7.85 497.81 10.00 13.00 3.00 0.23 14.52 T4 625

CH01503 3.05 4.57 1.52 3.50 16.52 10.00 15.00 5.00 0.10 0.48 T4 625

CH01505 0.00 0.18 0.18 1.51 419.92 0.00 0.60 0.60 0.04 12.25 T4 625

CH01507 0.00 3.66 3.66 2.06 216.71 0.00 12.00 12.00 0.06 6.32 T4 625

CH01507 Including 0.00 0.30 0.30 2.54 1299.31 0.00 1.00 1.00 0.07 37.90 T4 625

CH01507 and 0.30 1.22 0.91 2.57 304.63 1.00 4.00 3.00 0.07 8.88 T4 625

CH01509 0.00 0.49 0.49 6.21 284.68 0.00 1.60 1.60 0.18 8.30 T2 625 L

CH01511 0.00 0.91 0.91 4.77 15.15 0.00 3.00 3.00 0.14 0.44 T2 625 L

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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"

within the meaning of NI 43-101.

Quality Assurance (QA) – Quality Control (QC)

All underground face samples are collected by Company geologists from each of the active mining faces,

with samples transported by the geologists from Trixie to the on -site Company 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 Company's Burgin laboratory is not a certified analytical laboratory, but 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.

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.

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 BC, Canada, the 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 c onsiderable 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 mining 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 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 reporte d 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. Small scale test-mining at Trixie was suspended in December 2022, if and when test mining re-commences 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 decisio n to continue

such operations on a feasibility study, o r reported mineral resources or mineral reserves demonstrating economic and technical

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

Page 8 of 8

Cautionary Statement to U.S. Investors

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

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

Technical Reports, the Financial Statements, MD&A 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 Technical Report s, the Financial Statements, MD&A and this news

release, is not comparable to similar information made public by U.S. companies subject to the reporting and disclosure requirements

of the U.S. Securities and Exchange Commission ("SEC").

CAUTION REGARDING 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 invo lve 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; the utility and significance of historic data, including the significance of the district hosti ng past

producing mines; future mining activities; 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 potential of Trixie; the ability of the Company to expand mineral resources beyond current mineral resource estimates at Trixie;

the timing and ability of the Company to complete upgrades to the Trixie MRE (or any subsequent MRE) (if at all); the timing and

resumption of test mining activities at Trixie; the information and the scope of the contemplated Trixie MRE (and any subsequent

MRE); the impact of the Trixie MRE; the ability of the Company t o complete its exploration objectives in 2023 in the timing

contemplated (if at all); the ongoing advancement of the Trixie decline; the deposit remaining open for expansion at depth and down

plunge; the ability to realize upon any mineralization in a manner that 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 lookin g

information". Material assumptions also include, managemen t's perceptions of historical trends, the ability of exploration (including

drilling) to accurately predict mineralization, budget constraints and access to capital on terms acceptable to the Company, current

conditions and expected future developments, results of further exploration work to define or expand any mineral resources, as well

as other considerations that are believed to be appropriate in the circumstances. Osisko Development considers its assumption s 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 a nd

uncertainties that 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 and presence

of laws and regulations that may impose restrictions on mining; the ability of exploration activities (including drill results) to accurately

predict mineralization; errors in management's geological modelling; the ability to expand operations or complete further exploration

activities, including drilling; property and stream interests in the Tintic Project; the ability of the Company to obtain required approvals

and permits; the results of exploration activities; risks relating to exploration, development and mining activities; the global economic

climate; metal and commodity prices; fluctuations in the currency markets; dilution; environmental risks; and com munity, non-

governmental and governmental actions and the impact of stakeholder actions. 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, 202 2, as well as the

Financial Statements and MD&A for the year ended December 31, 2022, which have 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 information regarding the ri sks

and other factors applicable to the exploration results. Although the Company's believes the expectations conveyed by the for ward-

looking statements are reasonable based on information available as of the date hereof, no assurances can be given as to f uture

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. Forward-looking statements

are not guarantees of performance and 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.