• Completed 3 diamond drill holes totalling 1,026 metres.
• Intersected multiple horizons of strong mineralization including disseminated and semi-massive to massive sulphide hosted in fine- to medium-grained volcanic rocks.
• 117 core samples selected have been immediately sent to lab for analysis.

Vancouver, British Columbia--(Newsfile Corp. - March 20, 2025) - Sienna Resources Inc. (TSXV: SIE) (OTC Pink: SNNAF) (FSE: HRJ1) (FSE: A1XCQ0) ("Sienna" or the "Company") is pleased to announce that the Company has completed a 3-hole diamond drilling campaign at their 100% owned Case Lake Project, 80 km east of Cochrane, Ontario (Figure 1). The drilling program totalled 1,026 metres (Table 1). Significant intervals of sulphide mineralization were intersected, including intercepts with disseminated and semi-massive to massive mineralization (Figures 2 and 3), hosted in strongly sheared, intermediate volcanic successions, with regions of recrystallized gabbro and metasedimentary rocks (Table 2). A total of 117 core samples were collected and these have been prioritized for processing and shipping to the lab for analysis. Management cautions that until the assay results are reported by the lab, the Company is not certain of what concentration of metals, if any, will be contained in the drill core samples.

Jason Gigliotti, President of Sienna Resources Inc. stated, "We are pleased that the drilling was completed on time and on budget. I want to thank all involved for the great work. Based on what we have seen in the core, photos included, we are optimistic about the results from the drilling program and look forward to getting full assays back to determine the next course of action. We expect the results back in 2-6 weeks."

Figure 1. Sienna Resources' Case Lake Property location map.

About Sienna Resources Inc.

Sienna has significantly increased acreage of the "Stonesthrow Gold Project", consisting now of approximately 31,718 contiguous acres that are prospective for gold. Sienna has also recently acquired the 7,850 contiguous acres "Case Lake West Project" in Larder Lake Mining division of Ontario, Canada roughly 100 km north of Kirkland Lake, Northeast Ontario. Sienna has also recently acquired the 10,357 acre "Uranium Town Project" bordering Denison Mines Corporation (DML, DNN), the now 23,134 contiguous acre "Dragon Uranium Project", bordering Cameco Corporation (CCO, CCJ) and the 55,440 acre "Atomic Uranium Project" in the world-renowned Athabasca Basin of Saskatchewan. Also, Sienna has the "Elko Lithium Project" in Elko County, Nevada consisting of approximately 1,830 contiguous acres directly bordering Surge Battery Metals' (NILI) "Nevada North Lithium Project", who announced the highest-grade lithium deposit in the USA. Sienna is also one of the larger landholders in Clayton Valley, Nevada. Sienna's Clayton Valley projects include the Blue Clay Lithium Project, the Silver Peak South Project, and the Clayton Valley Deep Basin Lithium Project. Clayton Valley is home to the only lithium production in North America, that being Albemarle Corp's Silver Peak deposit. The Blue Clay Lithium Project is also near Tesla Motors Inc.'s Gigafactory in Nevada. On March 18, 2021, Schlumberger New Energy Venture announced the development of a lithium extraction pilot plant with a strategic partnership with Pure Energy. Management cautions that past results or discoveries on properties in proximity to Sienna may not necessarily be indicative of the presence of mineralization on the Company's properties.

Qualified Person:

Curtis Ferron MSc. P.Geo. a qualified person as defined by National Instrument 43-101 has reviewed and approved the scientific and technical disclosure contained within this news release.

We seek Safe Harbor.

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"Jason Gigliotti"
President, Director
Sienna Resources Inc.

Statements in this news release that are not historical facts are forward-looking statements. Forward-looking statements are statements that are not historical and consist primarily of projections - statements regarding future plans, expectations and developments. Words such as "expects", "intends", "plans", "may", "could", "potential", "should", "anticipates", "likely", "believes" and words of similar import tend to identify forward-looking statements. Forward-looking statements in this news release include uncertainty of exploration and development plans regarding the property; commodity price fluctuations; political or economic instability and regulatory changes; currency fluctuations, the state of the capital markets; uncertainty in the measurement of mineral reserves and resource estimates; the Company's ability to attract and retain qualified personnel and management; potential labour unrest; reclamation and closure requirements for mineral properties and the availability of capital to fund the Company's projects, as well as other risks and uncertainties identified under the heading "Risk Factors" in the Company's continuous disclosure documents filed on SEDAR. You are cautioned that the foregoing list is not exhaustive of all factors and assumptions which may have been used. The Company cannot assure you that actual events, performance or results will be consistent with these forward-looking statements, and management's assumptions may prove to be incorrect. These forward-looking statements reflect current expectations regarding future events and operating performance and speak only as of the date hereof and the Company does not assume any obligation to update forward-looking statements if circumstances or management's beliefs, expectations or opinions should change other than as required by applicable law. For the reasons set forth above, you should not place undue reliance on forward-looking statements.

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