Osisko Development Intercepts 610 G/T GOLD over 0.46 Meters IN

NYSE | TSXV: ODV NEWS RELEASE

Page 1 of 11

OSISKO DEVELOPMENT INTERCEPTS 610 g/t GOLD OVER 0.46 METERS IN

UNDERGROUND DRILLING AT TRIXIE, TINTIC PROJECT

Montreal, Québec, February 22, 2024 – Osisko Development Corp. (NYSE: ODV, TSXV: ODV)

("Osisko Development " or the "Company") is pleased to announce the remaining drilling and

underground chip sampling results from new development areas as part of its 2023 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.

DRILL ASSAY HIGHLIGHTS

This news release includes assays from fourteen underground diamond drill ("DD") holes (see Table 1).

Select assay highlights include:

• 66.04 grams per tonne ("g/t") gold ("Au") and 167.64 g/t silver ("Ag") over 8.99 meters ("m")

in TRXU-DD-23-072A (1.93 ounce per ton ("oz/t") Au and 4.89 oz/t Ag over 29.50 feet ("ft"))

including

o 610.00 g/t Au and 1,523.00 g/t Ag over 0.46 m (17.79 oz/t Au and 44.42 oz/t Ag over

1.50 ft)

o 180.00 g/t Au and 691.00 g/t Ag over 0.76 m (5.25 oz/t Au and 20.15 oz/t Ag over

2.50 ft)

• 23.89 g/t Au and 151.04 g/t Ag over 9.45 m in TRXU-DD-23-068 (0.70 oz/t Au and 4.41 oz/t

Ag over 31.00 ft) including

o 81.23 g/t Au and 98.14 g/t Ag over 0.76 m (2.37 oz/t Au and 2.86 oz/t Ag over 2.50

ft)

• 102.67 g/t Au and 740.43 g/t Ag over 1.07 m in TRXU -DD-23-061 (2.99 oz/t Au and 21.60

oz/t Ag over 3.50 ft) including

o 281.00 g/t Au and 1,644.00 g/t Ag over 0.30 m (8.20 oz/t Au and 47.95 oz/t Ag over

1.00 ft)

• 10.84 g/t Au and 35.29 g/t Ag over 4.57 m in TRXU -DD-23-066 (0.32 oz/t Au and 1.03 oz/t

Ag over 15.00 ft)

• 5.79 g/t Au and 101.98 g/t Ag over 13.72 m in TRXU-DD-23-065 (0.17 oz/t Au and 2.97 oz/t

Ag over 45.00 ft)

DRILL RESULTS SUMMARY

• In 2023, the company completed a total of 6, 028 m (19,776 ft) of underground drilling in 73

DD holes at Trixie. Assays have now been received for all 2023 holes testing the Trixie high

sulphidation epithermal Au-Ag targets. A new mineral resource estimate ("MRE") for the Trixie

deposit ("Trixie MRE") is in progress and is expected to be released in March 2024. The Trixie

MRE will include all underground drilling and chip sample assays from the 2023 program.

• One additional hole (TRXU-DD-23-073) was drilled to a depth of 759.6 m (2,492 ft) and targeted

a copper-gold porphyry target below Trixie. Assays for this hole are pending.

Page 2 of 11

• The focus of these recent holes was to test for mineralization along one of the priority target

areas south on strike from the known T2 domain, south towards the Sioux Ajax fault (see Figure

2). Results from holes TRXU-DD-23-065 (5.79 g/t Au over 13.72 m), TRXU-DD-23-066 (10.84

g/t over 4.57 m) and TRXU-DD-23-068 (23.89 g/t Au over 9.45 m) indicate that the

mineralization appears to be plunging to the south towards the Sioux Ajax Fault.

• One diamond drill rig is currently active at surface testing a copper-gold-molybdenum target at

Big Hill and is at a current depth of 922 m (3 ,028 ft). The target depth for this hole is

approximately 1,524 m (5,000 ft). Assays are pending for this drillhole.

UNDERGROUND CHIP SAMPLE ASSAY HIGHLIGHTS

Assay highlights include underground chip samples from 55 new development faces at Trixie. Of these,

25 faces had samples with greater than 1.0 g/t Au or greater than 50.0 g/t Ag values (see Table 2). The

remaining chip samples returned no significant assays. Selected assay highlights include:

• 123.67 g/t Au and 658.46 g/t Ag over 4.27 m in CH01683 (3.61 oz/t Au and 19.21 oz/t Ag

over 14.00 ft) including

o 717.86 g/t Au and 2,996.98 g/t Ag over 0.61 m (20.94 oz/t Au and 87.41 oz/t Ag over

2.00 ft)

• 40.84 g/t Au and 67.16 g/t Ag over 3.66 m in CH01694 (1.19 oz/t Au and 1.96 oz/t Ag over

12.00 ft) including

o 153.72 g/t Au and 227.32 g/t Ag over 0.91 m (4.48 oz/t Au and 6.63 oz/t Ag over

3.00 ft)

• 385.26 g/t Au and 1094.04 g/t Ag over 0.30 m in CH01687 (11.24 oz/t Au and 31.91 oz/t Ag

over 1.00 ft)

• 26.89 g/t Au and 186.63 g/t Ag over 3.05 m in CH01682 (0.78 oz/t Au and 5.44 oz/t Ag over

10.00 ft)

• 28.62 g/t Au and 150.08 g/t Ag over 2.23 m in CH01676 (0.83 oz/t Au and 4.38 oz/t Ag over

7.30 ft) including

o 62.60 g/t Au and 247.62 g/t Ag over 0.91 m (1.83 oz/t Au and 7.22 oz/t Ag over 3.00

ft)

• 7.74 g/t Au and 202.67 g/t Ag over 7.62 m in CH01679 (0.23 oz/t Au and 5.91 oz/t Ag over

25.00 ft)

• 18.48 g/t Au and 355.54 g/t Ag over 1.52 m in CH01664 (0.54 oz/t Au and 10.37 oz/t Ag over

5.00 ft)

CHIP SAMPLE SUMMARY

• Chip samples were collected in new development areas in the face and walls of exploration

crosscuts to explore along all domains of the Trixie deposit on the 625 Level, to the north

towards the Trixie Fault and to the south towards the Sioux Ajax Fault.

• The sampling and drilling results indicate that target areas to the north of Trixie and to the south

down plunge of the T2 structure are potentially mineralized and warrant further follow -up

exploration drilling and sampling to understand the extent of mineralization.

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 (14,200 acres of patented

mining claims and a further approximately 3,000 acres of overwhelmingly leased patented mining

claims) 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,

Page 3 of 11

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 comprise d 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 current MRE for the Trixie deposit (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.sedarplus.ca) and on EDGAR ( www.sec.gov) under Osisko Development's issuer profile and on

the Company's website at www.osiskodev.com.

Figure 1: Tintic Project – Trixie Area

Page 4 of 11

Figure 2: Trixie Long Section with Drill Highlights

Page 5 of 11

Figure 3: Trixie Long Section with Target Areas

Page 6 of 11

Table 1: Drilling Length Weighted Assay Composites at Trixie

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)

TRXU-DD-23-060 6.10 6.61 0.52 1.19 35.10 20.00 21.70 1.70 0.03 1.02

TRXU-DD-23-060 73.15 74.68 1.52 7.14 100.00 240.00 245.00 5.00 0.21 2.92

TRXU-DD-23-060 95.40 106.38 10.97 2.95 11.77 313.00 349.00 36.00 0.09 0.34

TRXU-DD-23-060 Including 102.84 103.94 1.10 22.53 77.10 337.40 341.00 3.60 0.66 2.25

TRXU-DD-23-060 110.79 113.54 2.74 1.51 6.59 363.50 372.50 9.00 0.04 0.19

TRXU-DD-23-061 36.12 37.19 1.07 102.67 740.43 118.50 122.00 3.50 2.99 21.60

TRXU-DD-23-061 Including 36.88 37.19 0.30 281.00 1,644.00 121.00 122.00 1.00 8.20 47.95

TRXU-DD-23-061 43.28 44.50 1.22 3.67 6.41 142.00 146.00 4.00 0.11 0.19

TRXU-DD-23-062 No Significant Assays

TRXU-DD-23-063 74.98 77.63 2.65 2.35 68.43 246.00 254.70 8.70 0.07 2.00

TRXU-DD-23-064 No Significant Assays

TRXU-DD-23-065 64.31 65.23 0.91 2.78 12.87 211.00 214.00 3.00 0.08 0.38

TRXU-DD-23-065 94.18 107.90 13.72 5.79 101.98 309.00 354.00 45.00 0.17 2.97

TRXU-DD-23-065 Including 97.23 98.76 1.52 8.24 11.86 319.00 324.00 5.00 0.24 0.35

TRXU-DD-23-065 and 100.68 101.35 0.67 11.09 254.00 330.30 332.50 2.20 0.32 7.41

TRXU-DD-23-065 and 101.80 102.93 1.13 18.73 230.00 334.00 337.70 3.70 0.55 6.71

TRXU-DD-23-065 and 104.70 106.38 1.68 12.04 508.00 343.50 349.00 5.50 0.35 14.82

TRXU-DD-23-066 65.07 67.97 2.90 13.01 140.85 213.50 223.00 9.50 0.38 4.11

TRXU-DD-23-066 65.07 66.60 1.52 19.96 206.00 213.50 218.50 5.00 0.58 6.01

TRXU-DD-23-066 79.86 81.23 1.37 2.14 30.27 262.00 266.50 4.50 0.06 0.88

TRXU-DD-23-066 87.78 89.00 1.22 7.90 133.00 288.00 292.00 4.00 0.23 3.88

TRXU-DD-23-066 98.45 99.97 1.52 3.20 5.60 323.00 328.00 5.00 0.09 0.16

TRXU-DD-23-066 103.33 107.90 4.57 10.84 35.29 339.00 354.00 15.00 0.32 1.03

TRXU-DD-23-067 No Significant Assays

TRXU-DD-23-068 75.59 85.04 9.45 23.89 151.04 248.00 279.00 31.00 0.70 4.41

TRXU-DD-23-068 Including 75.59 76.20 0.61 33.56 140.00 248.00 250.00 2.00 0.98 4.08

TRXU-DD-23-068 and 76.20 76.96 0.76 81.23 98.14 250.00 252.50 2.50 2.37 2.86

TRXU-DD-23-068 and 78.33 79.25 0.91 26.95 120.00 257.00 260.00 3.00 0.79 3.50

TRXU-DD-23-068 and 80.62 81.69 1.07 37.34 220.00 264.50 268.00 3.50 1.09 6.42

TRXU-DD-23-068 and 81.69 82.30 0.61 52.50 330.00 268.00 270.00 2.00 1.53 9.63

TRXU-DD-23-068 and 84.43 85.04 0.61 23.03 530.00 277.00 279.00 2.00 0.67 15.46

TRXU-DD-23-069 102.11 108.81 6.71 3.06 10.33 335.00 357.00 22.00 0.09 0.30

TRXU-DD-23-069 Including 106.22 106.98 0.76 5.34 7.98 348.50 351.00 2.50 0.16 0.23

TRXU-DD-23-069 and 106.98 107.90 0.91 8.00 25.90 351.00 354.00 3.00 0.23 0.76

TRXU-DD-23-070 28.35 31.39 3.05 6.94 12.00 93.00 103.00 10.00 0.20 0.35

TRXU-DD-23-070 Including 30.18 31.39 1.22 9.27 20.00 99.00 103.00 4.00 0.27 0.58

TRXU-DD-23-071 6.10 7.01 0.91 3.41 16.00 20.00 23.00 3.00 0.10 0.47

TRXU-DD-23-071 9.91 10.36 0.46 19.45 73.00 32.50 34.00 1.50 0.57 2.13

TRXU-DD-23-071 17.53 18.59 1.07 4.70 44.00 57.50 61.00 3.50 0.14 1.28

TRXU-DD-23-071 21.64 23.01 1.37 7.70 21.00 71.00 75.50 4.50 0.22 0.61

Page 7 of 11

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)

TRXU-DD-23-071 25.30 27.13 1.83 4.88 14.58 83.00 89.00 6.00 0.14 0.43

TRXU-DD-23-072 1.22 2.13 0.91 2.03 20.00 4.00 7.00 3.00 0.06 0.58

TRXU-DD-23-072 6.71 7.47 0.76 2.30 12.00 22.00 24.50 2.50 0.07 0.35

TRXU-DD-23-072 9.45 10.36 0.91 10.66 71.00 31.00 34.00 3.00 0.31 2.07

TRXU-DD-23-072 13.56 18.14 4.57 3.32 3.00 44.50 59.50 15.00 0.10 0.09

TRXU-DD-23-072 Including 13.56 14.33 0.76 6.36 0.00 44.50 47.00 2.50 0.19 0.00

TRXU-DD-23-072 and 17.22 18.14 0.91 5.80 15.00 56.50 59.50 3.00 0.17 0.44

TRXU-DD-23-072A 9.45 10.06 0.61 5.84 38.00 31.00 33.00 2.00 0.17 1.11

TRXU-DD-23-072A 13.41 22.56 9.14 2.94 11.45 44.00 74.00 30.00 0.09 0.33

TRXU-DD-23-072A 23.47 32.46 8.99 66.04 167.64 77.00 106.50 29.50 1.93 4.89

TRXU-DD-23-072A Including 25.91 26.52 0.61 9.62 53.00 85.00 87.00 2.00 0.28 1.55

TRXU-DD-23-072A and 30.18 30.63 0.46 23.04 254.00 99.00 100.50 1.50 0.67 7.41

TRXU-DD-23-072A and 30.63 31.09 0.46 610.00 1,523.00 100.50 102.00 1.50 17.79 44.42

TRXU-DD-23-072A and 31.09 31.85 0.76 180.00 691.00 102.00 104.50 2.50 5.25 20.15

Table 2: Face Chip Sample Length Weighted Assay Composites at Trixie

Site 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)

CH01661 1.52 3.05 1.52 1.20 0.00 5.00 10.00 5.00 0.04 0.00

CH01664 4.57 6.10 1.52 18.48 355.54 15.00 20.00 5.00 0.54 10.37

CH01667 3.05 4.57 1.52 1.03 13.75 10.00 15.00 5.00 0.03 0.40

CH01670 0.00 3.84 3.84 4.17 51.40 0.00 12.60 12.60 0.12 1.50

CH01670 Including 1.95 3.05 1.10 7.37 136.99 6.40 10.00 3.60 0.21 4.00

CH01672 3.05 4.57 1.52 1.68 13.09 10.00 15.00 5.00 0.05 0.38

CH01674 0.52 1.37 0.85 2.37 32.88 1.70 4.50 2.80 0.07 0.96

CH01674 3.96 4.57 0.61 6.31 231.80 13.00 15.00 2.00 0.18 6.76

CH01676 1.43 3.66 2.23 28.62 150.08 4.70 12.00 7.30 0.83 4.38

CH01676 Including 1.83 2.74 0.91 62.60 247.62 6.00 9.00 3.00 1.83 7.22

CH01677 0.67 0.88 0.21 19.44 1364.11 2.20 2.90 0.70 0.57 39.79

CH01678 3.81 4.57 0.76 1.30 20.40 12.50 15.00 2.50 0.04 0.59

CH01679 0.00 7.62 7.62 7.74 202.67 0.00 25.00 25.00 0.23 5.91

CH01679 Including 5.49 6.10 0.61 18.00 386.36 18.00 20.00 2.00 0.52 11.27

CH01679 and 6.10 6.71 0.61 29.35 560.88 20.00 22.00 2.00 0.86 16.36

CH01680 0.00 4.57 4.57 2.72 97.08 0.00 15.00 15.00 0.08 2.83

CH01682 4.57 7.62 3.05 26.89 186.63 15.00 25.00 10.00 0.78 5.44

CH01682 Including 4.57 4.88 0.30 77.34 439.29 15.00 16.00 1.00 2.26 12.81

CH01682 and 6.40 7.62 1.22 41.10 290.02 21.00 25.00 4.00 1.20 8.46

CH01683 0.00 4.27 4.27 123.67 658.46 0.00 14.00 14.00 3.61 19.21

CH01683 Including 0.00 0.34 0.34 103.67 583.89 0.00 1.10 1.10 3.02 17.03

CH01683 and 0.64 0.88 0.24 134.02 1961.66 2.10 2.90 0.80 3.91 57.22

Page 8 of 11

Site 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)

CH01683 and 1.80 2.04 0.24 40.25 195.20 5.90 6.70 0.80 1.17 5.69

CH01683 and 3.66 4.27 0.61 717.86 2,996.98 12.00 14.00 2.00 20.94 87.41

CH01686 3.05 3.66 0.61 5.35 60.37 10.00 12.00 2.00 0.16 1.76

CH01687 0.00 0.30 0.30 385.26 1,094.04 0.00 1.00 1.00 11.24 31.91

CH01689 0.00 1.07 1.07 2.13 8.23 0.00 3.50 3.50 0.06 0.24

CH01690 0.00 7.19 7.19 2.38 31.17 0.00 23.60 23.60 0.07 0.91

CH01690 Including 3.29 4.02 0.73 4.94 117.96 10.80 13.20 2.40 0.14 3.44

CH01692 1.77 4.39 2.62 2.85 41.40 5.80 14.40 8.60 0.08 1.21

CH01692 1.77 2.19 0.43 4.53 132.43 5.80 7.20 1.40 0.13 3.86

CH01694 0.91 4.57 3.66 40.84 67.16 3.00 15.00 12.00 1.19 1.96

CH01694 Including 3.66 4.57 0.91 153.72 227.32 12.00 15.00 3.00 4.48 6.63

CH01696 0.00 0.91 0.91 2.23 43.16 0.00 3.00 3.00 0.06 1.26

CH01698 1.52 3.66 2.13 4.31 28.81 5.00 12.00 7.00 0.13 0.84

CH01698 Including 1.52 1.83 0.30 20.84 137.68 5.00 6.00 1.00 0.61 4.02

CH01699 0.00 1.52 1.52 2.30 4.56 0.00 5.00 5.00 0.07 0.13

CH01705 2.68 4.05 1.37 2.57 59.75 8.80 13.30 4.50 0.07 1.74

CH01707 0.00 0.91 0.91 3.09 37.47 0.00 3.00 3.00 0.09 1.09

CH01708 0.91 4.57 3.66 2.99 20.77 3.00 15.00 12.00 0.09 0.61

CH01708 Including 0.91 1.83 0.91 5.73 25.27 3.00 6.00 3.00 0.17 0.74