OSISKO DEVELOPMENT REPORTS 2022 DRILL RESULTS AT TRIXIE, INCLUDING: 28.72 g/t Au and 404 g/t Ag over 6.25 m and 27.26 g/t Au and 96.98 g/t Ag over 4.57 m

NYSE: ODV TSXV: ODV NEWS RELEASE

Page 1 of 11

OSISKO DEVELOPMENT REPORTS 2022 DRILL RESULTS AT TRIXIE, INCLUDING:

28.72 g/t Au and 404 g/t Ag over 6.25 m and 27.26 g/t Au and 96.98 g/t Ag over 4.57 m

Montreal, Québec, April 3, 2023 – Osisko Development Corp. (NYSE: ODV, TSXV: ODV) ("Osisko

Development" or the "Company") is pleased to announce underground diamond drilling ("DD") results as

part of 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, "Today's drill results include high-grade

gold intercepts from the Trixie underground in all domains of the deposit including the gold and silver rich

tellurides in the T2 structure, the quartz barite stockwork T4 zone with gold bearing fissures similar to T2 ,

and the 75-85 polymetallic silica -sulphide cemented breccia zone. These new drill results continue to

validate our exploration work and expand our understanding of known mineralization to generate additional

exploration targets at structural and lithological contacts beneath the overlying Ophir shale cap rock."

DRILL ASSAY HIGHLIGHTS

This news release includes assays from 42 DD holes (refer to Table 1). Select assay highlights include:

• 48.20 grams per tonne (" g/t") gold ("Au") and 30.60 g/t silver ("Ag") over 0.76 meters ("m")

(1.41 troy ounces per short ton ("oz/t") Au and 0.89 oz/t Ag over 2.50 ft.) in hole TUG-625-032

• 354.00 g/t Au and 249.00 g/t Ag over 0.46 m (10.33 oz/t Au and 7.26 oz/t Ag over 1.50 ft.) in hole

TUG-625-033

• 32.89 g/t Au and 41.86 g/t Ag over 3.20 m (0.96 oz/t Au and 1.22 oz/t Ag over 10.50 ft.) in hole

TUG-625-035 including

o 76.80 g/t Au and 68.60 g/t Ag over 1.01 m (2.24 oz/t Au and 2.00 oz/t Ag over 3.30 ft.)

• 67.01 g/t Au and 207.55 g/t Ag over 0.94 m (1.95 oz/t Au and 6.05 oz/t Ag over 3.1 0 ft.) in hole

TUG-625-038 including

o 240.00 g/t Au and 860.00 g/t Ag over 0.18 m (7.00 oz/t Au and 25.08 oz/t Ag over 0.60 ft.)

• 13.44 g/t Au and 71.36 g/t Ag over 3.05 m (0.39 oz/t Au and 2.08 oz/t Ag over 10.00 ft.) in hole

TUG-625-051

• 10.68 g/t Au and 32.59 g/t Ag over 4.88 m (0.31 oz/t Au and 0.95 oz/t Ag over 16 ft.) in hole TUG-

625-052 including

o 27.20 g/t Au and 52.1 g/t Ag over 1.13 m (0.79 oz/t Au and 1.52 oz/t Ag over 3.70 ft.) in

hole TUG-625-052

• 91.30 g/t Au and 18.70 g/t Ag over 1.34 m (2.66 oz/t Au and 0.55 oz/t Ag over 4.40 ft.) in hole

TUG-625-053

• 27.26 g/t Au and 96.98 g/t Ag over 4.57 m (0.80 oz/t Au and 2.83 oz/t Ag over 15.00 ft.) in hole

TUG-625-086 including

o 39.10 g/t Au and 244.00 g/t Ag over 0.79 m (1.14 oz/t Au and 7.12 oz/t Ag over 2.60 ft.)

and

o 54.50 g/t Au and 105.00 g/t Ag over 1.22 m (1.59 oz/t Au and 3.06 oz/t Ag over 4.00 ft.)

• 46.50 g/t Au and 98.80 g/t Ag over 2.74 m (1.36 oz/t Au and 2.88 oz/t Ag over 9.00 ft.) in hole

TUG-625-086

• 28.72 g/t Au and 404.19 g/t Ag over 6.25 m (0.84 oz/t Au and 11.79 oz/t Ag over 20.50 ft.) in hole

TUG-625-087 including

Page 2 of 11

o 81.50 g/t Au and 1,240.00 g/t Ag over 0.61 m (2.38 oz/t Au and 36.17 oz/t Ag over 2.00

ft.) and

o 118.00 g/t Au and 968.00 g/t Ag over 0.46 m (3.44 oz/t Au and 28.23 oz/t Ag over 1.50 ft.)

• 12.64 g/t Au and 92.58 g/t Ag over 5.18 m (0.37 oz/t Au and 2.70 oz/t Ag over 17.00 ft.) in hole

TUG-625-088 including

o 31.50 g/t Au and 162.00 g/t Ag over 1.22 m (0.92 oz/t Au and 4.73 oz/t Ag over 4.00 ft.)

• 12.46 g/t Au and 95.05 g/t Ag over 4.57 m (0.36 oz/t Au and 2.77 oz/t Ag over 15.00 ft.) in hole

TUG-625-093 including

o 47.20 g/t Au and 272.00 g/t Ag over 0.76 m (1.38 oz/t Au and 7.93 oz/t Ag over 2.50 ft.)

• 52.30 g/t Au and 325.00 g/t Ag over 1.13 m (1.53 oz/t Au and 9.48 oz/t Ag over 3.70 ft.) in hole

TUG-625-099

• 31.00 g/t Au and 91.30 g/t Ag over 1.07 m (0.90 oz/t Au and 2.66 oz/t Ag over 3.50 ft.) in hole

TUG-625-101

• 229.00 g/t Au and 238.00 g/t Ag over 0.76 m (6.68 oz/t Au and 6.94 oz/t Ag over 2.50 ft.) in hole

TUG-625-102A

• 19.77 g/t Au and 76.67 g/t Ag over 4.57 m (0.58 oz/t Au and 2.24 oz/t Ag over 15.00 ft.) in hole

TUG-625-103

DRILL SUMMARY

• The high-grade intercepts disclosed in the news release are located on the southern portion of the

current Trixie Mineral Resource Estimate ("Trixie MRE") along new development and stepping out

closer to the Sioux Ajax Fault, one of the main targets for mineralization at Trixie.

• The T2 structure continues to intersect high-grade mineralization including 91.3 g/t Au and 18.7 g/t

Ag over 1.34 m in hole TUG-625-053.

• The T4 stockwork , in the immediate hangingwall of the T2 structure, exhibits high -grade fissure

structures similar to the T2 within a broader zone and returned assays including 354 g /t Au and

249 g/t Ag over 0.46 m in hole TUG-625-033 and 229 g/t Au and 238 g/t Au over 0.76 m in hole

TUG-625-102A (see Figure 2).

• The new drilling results indicate consistent mineralization at the contact between the 75-85, T4

stockwork and overlying Ophir Shale including hole TUG-625-087 that assayed 28.72 g/t Au and

404.19 g/t Ag over 6.25 m (see Figure 3).

• The 75 -85 domain consists of a discrete north -south striking moderate to steeply west -dipping

polymetallic silica -sulphide cemented breccia zone. The domain connects two historically

developed tabular mineralized bodies, the 756 at the north end of Trixie development, and the 75-

85 mineralized shoot to the south. Historically documented primary economic minerals include a

native gold and silver, copper, lead and/or zinc bearing sulphides and sulphosalts. Gangue (non-

mineralized) minerals are chiefly crystalline quartz and barite.

EXPLORATION NEXT STEPS

• The Company currently has two underground diamond drill rigs in operation at Trixie conducting

exploration activities.

• Follow up exploration targets include drill testing of the contact beneath the Ophir Shale cap rock,

where mineralization appears to be concentrated, as well as testing the 75-85 structure at depth.

• In 2022, the Company completed 28 surface reverse circulation ( "RC") drill holes near Trixie

totalling approximately 8,442 m (27,700 ft.) and 62 underground DD holes in the 625 level at Trixie

totalling approximately 3,232 m (10,060 ft.). To date, assays have been received for 8 RC drill holes

and 56 DD holes.

Corporate Update

The board of directors (the "Board") of the Company has approved the grant of an aggregate of 1,081,600

incentive stock options (the " Options") and an aggregate of 219,000 restricted share units (" RSUs") to

certain senior officers of the Company, in accordance with the terms of the Company's current Option and

RSU plans, as applicable. The aforementioned Option and RSU grants constitute the annual equity-based

compensation grants of the Company, consistent with the Company's regular compensation cycle. The

Page 3 of 11

Options are exercisable at a price of C$6.59 per share of the Company (based on the closing price of

March 31, 2023) and will expire on April 3, 2028. Vesting of Options will occur in three equal parts on the

following dates: April 3, 2024, April 3, 2025, and April 3, 2026, respectively. The RSUs will cliff vest on April

3, 2026.

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.

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 representativ es 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.

Page 4 of 11

Figure 1: Trixie Project Area

Page 5 of 11

Figure 2: Drill Plan Map

Page 6 of 11

Figure 3: Cross Section of Underground Drilling at 625 L at Trixie

Page 7 of 11

Table 1: Drilling 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) Comments

TUG-625-030 5.88 8.23 2.35 4.15 10.55 19.30 27.00 7.70 0.12 0.31 T4

TUG-625-030B 10.61 12.04 1.43 2.47 6.70 34.80 39.50 4.70 0.07 0.20 T4

TUG-625-031 10.21 11.77 1.55 3.19 9.23 33.50 38.60 5.10 0.09 0.27 T4

TUG-625-031 35.54 36.88 1.34 8.97 4.36 116.60 121.00 4.40 0.26 0.13 T2

TUG-625-032 3.05 4.57 1.52 2.65 10.30 10.00 15.00 5.00 0.08 0.30 T4

TUG-625-032 7.62 8.38 0.76 48.20 30.60 25.00 27.50 2.50 1.41 0.89 T4

TUG-625-032 27.13 31.24 4.11 0.43 41.40 89.00 102.50 13.50 0.01 1.21 T2 15 m down dip

TUG-625-032 Including 27.13 28.65 1.52 0.49 77.30 89.00 94.00 5.00 0.01 2.25 T2 15 m down dip

TUG-625-032 56.39 57.30 0.91 8.09 105.00 185.00 188.00 3.00 0.24 3.06 T2 footwall

TUG-625-033 3.51 3.96 0.46 354.00 249.00 11.50 13.00 1.50 10.33 7.26 T4

TUG-625-033 19.20 19.96 0.76 12.75 59.30 63.00 65.50 2.50 0.37 1.73 T4

TUG-625-033 25.24 25.76 0.52 53.55 65.37 82.80 84.50 1.70 1.56 1.91 T2 10 m down dip

TUG-625-033 Including 25.24 25.42 0.18 76.00 104.00 82.80 83.40 0.60 2.22 3.03 T2 10 m down dip

TUG-625-035 1.52 4.72 3.20 32.89 41.86 5.00 15.50 10.50 0.96 1.22 T4

TUG-625-035 Including 1.52 2.29 0.76 35.00 79.00 5.00 7.50 2.50 1.02 2.30 T4

TUG-625-035 and 3.72 4.72 1.01 76.80 68.60 12.20 15.50 3.30 2.24 2.00 T4

TUG-625-035 16.76 18.29 1.52 3.42 93.80 55.00 60.00 5.00 0.10 2.74 T4

TUG-625-038 3.51 4.45 0.94 67.01 207.55 11.50 14.60 3.10 1.95 6.05 T4

TUG-625-038 Including 3.51 3.84 0.34 57.50 112.00 11.50 12.60 1.10 1.68 3.27 T4

TUG-625-038 and 4.27 4.45 0.18 240.00 860.00 14.00 14.60 0.60 7.00 25.08 T4

TUG-625-038 19.20 19.81 0.61 3.26 19.20 63.00 65.00 2.00 0.10 0.56 T4

TUG-625-038 26.82 27.74 0.91 0.23 158.33 88.00 91.00 3.00 0.01 4.62 75-85

TUG-625-039 1.83 5.18 3.35 3.38 8.58 6.00 17.00 11.00 0.10 0.25 T4

TUG-625-040 4.72 5.79 1.07 9.03 26.80 15.50 19.00 3.50 0.26 0.78 T4

TUG-625-040 8.84 11.03 2.19 4.44 6.46 29.00 36.20 7.20 0.13 0.19 T2

TUG-625-041 9.14 10.06 0.91 7.58 16.60 30.00 33.00 3.00 0.22 0.48 T4

TUG-625-041 18.90 21.34 2.44 2.36 47.80 62.00 70.00 8.00 0.07 1.39 T4

TUG-625-042

No Significant

Assays East of T4 HW

TUG-625-043

No Significant

Assays East of T4 HW

TUG-625-051 3.05 3.96 0.91 11.25 57.90 10.00 13.00 3.00 0.33 1.69 T4

TUG-625-051 12.89 17.22 4.33 4.43 14.87 42.30 56.50 14.20 0.13 0.43 T4

TUG-625-051 Including 15.30 15.85 0.55 15.95 67.00 50.20 52.00 1.80 0.47 1.95 T4

TUG-625-051 25.91 28.96 3.05 13.44 71.36 85.00 95.00 10.00 0.39 2.08 75-85

TUG-625-051 Including 25.91 27.28 1.37 18.60 129.00 85.00 89.50 4.50 0.54 3.76 75-85

TUG-625-052 23.16 28.04 4.88 10.68 32.59 76.00 92.00 16.00 0.31 0.95 75-85

Page 8 of 11

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) Comments

TUG-625-052 Including 23.16 24.29 1.13 27.20 52.10 76.00 79.70 3.70 0.79 1.52 75-85

TUG-625-052 and 25.91 28.04 2.13 7.93 36.20 85.00 92.00 7.00 0.23 1.06 75-85

TUG-625-053 0.00 0.98 0.98 16.15 11.20 0.00 3.20 3.20 0.47 0.33 T4

TUG-625-053 17.37 17.98 0.61 3.37 5.99 57.00 59.00 2.00 0.10 0.17 T4

TUG-625-053 21.34 22.56 1.22 5.73 35.70 70.00 74.00 4.00 0.17 1.04 T4

TUG-625-053 27.13 31.00 3.87 2.96 24.93 89.00 101.70 12.70 0.09 0.73 T4

TUG-625-053 34.32 35.66 1.34 91.30 18.70 112.60 117.00 4.40 2.66 0.55 T2

TUG-625-054 16.00 17.22 1.22 11.35 44.00 52.50 56.50 4.00 0.33 1.28 T4

TUG-625-054 47.85 49.07 1.22 4.48 41.50 157.00 161.00 4.00 0.13 1.21 T2 Footwall

TUG-625-055 12.80 13.26 0.46 2.23 17.00 42.00 43.50 1.50 0.07 0.50 T4

TUG-625-055 34.35 35.11 0.76 2.18 26.00 112.70 115.20 2.50 0.06 0.76 T4

TUG-625-059

No Significant

Assays

Exploration hole,

east of Trixie

Decline

TUG-625-061

No Significant

Assays T4

TUG-625-062 33.68 34.44 0.76 11.17 23.07 110.50 113.00 2.50 0.33 0.67 T4

TUG-625-062 including 33.68 33.83 0.15 46.60 94.30 110.50 111.00 0.50 1.36 2.75 T4

TUG-625-063 42.06 45.42 3.35 7.74 25.41 138.00 149.00 11.00 0.23 0.74 T2 12 m down dip

TUG-625-083

No Significant

Assays T4

TUG-625-084 44.96 45.14 0.18 73.50 88.30 147.50 148.10 0.60 2.14 2.58 T2

TUG-625-086 0.00 4.57 4.57 27.26 96.98 0.00 15.00 15.00 0.80 2.83 T4

TUG-625-086 Including 0.00 0.79 0.79 39.10 244.00 0.00 2.60 2.60 1.14 7.12 T4

TUG-625-086 and 1.83 3.05 1.22 54.50 105.00 6.00 10.00 4.00 1.59 3.06 T4

TUG-625-086 10.36 11.89 1.52 5.00 8.91 34.00 39.00 5.00 0.15 0.26 T4

TUG-625-086 14.48 14.78 0.30 0.99 94.00 47.50 48.50 1.00 0.03 2.74 T4

TUG-625-086 17.98 20.73 2.74 46.50 98.80 59.00 68.00 9.00 1.36 2.88 75-85

TUG-625-087 0.00 5.49 5.49 2.18 33.86 0.00 18.00 18.00 0.06 0.99 T4

TUG-625-087 16.46 22.71 6.25 28.72 404.19 54.00 74.50 20.50 0.84 11.79 75-85

TUG-625-087 Including 16.46 17.07 0.61 81.50 1240.00 54.00 56.00 2.00 2.38 36.17 75-85

TUG-625-087 and 17.07 17.68 0.61 37.60 723.00 56.00 58.00 2.00 1.10 21.09 75-85

TUG-625-087 and 17.68 18.14 0.46 118.00 968.00 58.00 59.50 1.50 3.44 28.23 75-85

TUG-625-087 and 18.14 18.75 0.61 43.90 406.00 59.50 61.50 2.00 1.28 11.84 75-85

TUG-625-088 22.25 27.43 5.18 12.64 92.58 73.00 90.00 17.00 0.37 2.70 75-85

TUG-625-088 Including 24.38 24.99 0.61 22.00 175.00 80.00 82.00 2.00 0.64 5.10 75-85

TUG-625-088 and 25.60 26.82 1.22 31.50 162.00 84.00 88.00 4.00 0.92 4.73 75-85

TUG-625-088 and 26.82 27.43 0.61 9.64 92.00 88.00 90.00 2.00 0.28 2.68 75-85

TUG-625-089 10.36 12.04 1.68 2.12 17.20 34.00 39.50 5.50 0.06 0.50 T4

TUG-625-090 3.11 3.96 0.85 14.00 194.00 10.20 13.00 2.80 0.41 5.66 T4

TUG-625-091 15.54 20.27 4.72 2.97 52.30 51.00 66.50 15.50 0.09 1.53 T2