Radisson Continues to Expand Scope of High-Grade Gold Mineralization Beneath the Former O'Brien Gold Mine with New Drill Results Including 68.24 g/t Gold over 6.2 Metres

Rouyn-Noranda, Quebec, Sept 21, 2026 - (ACN Newswire) - Radisson Mining Resources Inc. (TSXV: RDS) (OTCQX: RMRDF) ("Radisson" or the "Company") is pleased to announce the results of eight new drill holes recently completed at its 100%-owned O'Brien Gold Project ("O'Brien" or the "Project") located in the Abitibi region of Québec. The eight holes form part of two clusters of drill holes based on pilot holes and wedge branches that are serving to delineate an important system of high-grade mineralization in multiple quartz-sulphide-gold veins over a now 1,000-metre vertical interval beneath the former O'Brien Gold Mine. These results are the latest from the Company's ongoing 140,000-metre step-out drill program designed to test the full scope of gold mineralization at the Project.

All eight drill holes reported today returned significant gold mineralization. Highlights (Figure 1 and Table 1) include:

OB-26-385W5 intersected 68.24 grams per tonne ("g/t") gold ("Au") over 6.20 metres (core lengths) including 384.01 g/t Au over 1.0 metre and including 28.68 g/t Au over 1.0 metre (residual intercept grade of 2.48 g/t Au);

OB-26-385W8 intersected 27.27 g/t Au over 3.3 metres including 72.40 g/t Au over 1.2 metres (residual intercept grade of 1.49 g/t Au), and 3.90 g/t Au over 9.3 metres including 6.10 g/t Au over 2.0 metres and including 5.78 g/t Au over 1.2 metres (residual intercept grade of 2.81 g/t Au), and 8.35 g/t Au over 4.0 metres including 16.10 g/t Au over 1.5 metres (residual intercept grade of 3.7 g/t Au);

OB-25-378W4 intersected 8.14 g/t Au over 5.50 metres including 11.52 g/t Au over 3.70 metres (residual intercept grade of 1.19 g/t Au);

OB-26-385W7 intersected 18.13 g/t Au over 2.0 metres including 34.91 g/t Au over 1.0 metre (residual intercept grade of 1.35 g/t Au); and

OB-25-378W5 intersected 3.90 g/t Au over 9.3 metres including 16.84 g/t Au over 1.4 metres (residual intercept grade of 1.60 g/t Au) and 4.00 g/t Au over 4.60 metres.

Matt Manson, President and CEO: "Since the beginning of our deep step-out drilling program at O'Brien in late 2024, we have enjoyed consistent success in expanding the scope of mineralization beyond the former mine and the historical mineral resources. Of the 128 drill holes completed during this period,106 have returned drill intercepts with grades and thicknesses consistent with our mineral resources. This is an impressive 83% "hit" rate (Table 2), and we report every hole completed. We continue to see a consistent pattern of high-grade quartz-sulphide-gold veins within broader, mineralized alteration halos. These mineralized zones form parallel vein packages within the host Piché Group rocks, with good continuity across adjacent drill holes and over significant distances. The two clusters of new drill results reported today are delineating the important "O'Brien Mine East" trend at its top, immediately below the former mine workings, and extending it downwards at up to 2 kilometres vertical depth. In our reporting of drill results, as with today's news, we show the grade of the full interval across the mineralized zone (in core lengths at a 1 g/t Au bottom cut-off) and the "including" interval representing the high-grade quartz-sulphide-gold vein within the zone. The intercept's residual grade, which represents grade in the alteration halo, is typically between 1 g/t Au and 4 g/t Au. These patterns are all demonstrated reliably in today's results. O'Brien is clearly a large scale and increasingly predictable gold mineralizing system. Drilling is ongoing with eight rigs active at the Project."

Figure 1: Longitudinal Vertical Section and Plan View of Gold Vein Mineralization and Mineral Resources at the O'Brien Gold Project, with Today's Drill Holes Illustrated

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Gold Mineralization at O'Brien

Gold mineralizing quartz-sulphide veins at O'Brien occur within a thin band of interlayered mafic volcanic rocks, conglomerates, and porphyritic andesitic sills of the Piché Group occurring in contact with the east-west oriented Larder Lake-Cadillac Break ("LLCB"). Gold, along with pyrite and arsenopyrite, is typically associated with shearing and a pervasive biotite alteration, and developed within multiple Piché Group lithologies and, occasionally, the hanging-wall Pontiac and footwall Cadillac meta-sedimentary rocks.

As mapped at the historic O'Brien mine, and now replicated in the modern drilling, individual veins are generally narrow, ranging from several centimetres up to several metres in thickness and are associated with broader, mineralized alteration envelopes. Multiple veins occur sub-parallel to each other, as well as sub-parallel to the Piché lithologies and the LLCB. Individual veins have well-established lateral continuity, with steeply plunging grade shoots developed over significant lengths. The historic O'Brien mine produced over half a million ounces of gold from such veins and shoots at an average grade exceeding 15 g/t Au and over a vertical extent of at least 1,000 metres. Modern exploration has focussed on delineating well-developed vein mineralization below and to the east of the historic mine. Based on the historic data available, it is clear that the former mine was "high-graded", with mining focused on a main central stope and parallel veins identified but left undeveloped.

Figure 2: Visible gold in OB-26-385W5 yielding 384.01 g/t Au over 1.0 metre between 1,514.2 metres and 1,515.2 metres, within a broader intercept averaging 68.24 g/t Au over 6.2 Metres between 1,511 metres and 1,517.2 metres

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Table 1: Assay Results Calculated at a 3 g/t Au Bottom Cut-Off from Drill Holes Published Today

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Notes on Calculation of Drill Intercepts:
The O'Brien Gold Project Mineral Resource Estimate effective January 31, 2026 utilizes a 2.20 g/t Au bottom cut-off, a US$2,500 gold price, a minimum mining width of 1.2 metres, and a 60 g/t Au upper cap on individual assays. Intercepts presented in Table 1 are calculated with a 3.00 g/t Au bottom cut-off. Sample grades are uncapped. True widths, based on depth of intercept and drill hole inclination, are estimated to be 30-80% of core length. Table 3 presents additional drill intercepts calculated with a 1.00 g/t Au bottom cut-off over a minimum 1.0 metre core length so as to illustrate the frequency and continuity of mineralized intervals within which high-grade gold veins at O'Brien are developed. Lithology Codes: PON-S3: Pontiac Sediments; V3-S, V3-N, V3-CEN: Basalt-South, North, Central; S1P, S3P: Conglomerate and Greywackes; POR-S, POR-N: Porphyry South, North; TX: Crystal Tuff; ZFLLC: Larder Lake-Cadillac Fault Zone.

Step-Out Drilling at O'Brien

Since the end of 2024, Radisson has been pursuing a program of broad step-outs beneath the historic O'Brien Gold mine and the existing mineral resources designed to test the extent of gold mineralization at the Project. This drilling is accomplished with pilot holes followed by wedges and directional drilling to maximize drill efficiency and minimize costs. In October 2025, Radisson announced the expansion of the step-out drill program to 140,000 metres employing eight drill rigs (see Radisson news release dated October 16, 2025).

The origin of the step-out drill program was the deep pilot hole OB-24-337, which was the first exploration drill hole located below the former mine workings since mining ended in 1957. This hole intersected 31.24 g/t Au over 8.0 metres, including 242.0 g/t Au over 1.0 m at approximately 1,500 metres vertical depth (see Radisson news release dated December 16, 2024). Fifteen wedge branches were completed from OB-24-337 delineating up to eight gold-bearing veins over a 250-metre by 700-metre area in what is referred to as "O'Brien Mine East" (see Radisson news release dated February 12, 2026). In March 2026, Radisson published an interim update in the Project's mineral resources, showing meaningful growth based on the on-going drilling (see Radisson news release dated March 2, 2026).

The focus of the step-out drill program has been the extension of mineralization at depth, with an exploration floor of 2 kilometres depth, and recently announced plans to extend this drilling to 2.5 kilometres depth (see Radisson news release dated May 28, 2026). Given the character of neighbouring gold deposits and the wealth of mining infrastructure within or close to the O'Brien Gold Project, Radisson believes that significant exploration potential exists to these depths, and such mineralization might reasonably be expected to be developed. Drilling has recently confirmed the extension of the "Trend 1" zone of mineralization to 1.9 kilometres vertical depth (see Radisson news release dated April 30, 2026).

In addition to the progressively deeper drilling, the 140,000-metre program includes targeting of areas within the O'Brien geological model that have not previously been tested and offer the potential for additional mineral resources at shallower depths. Positive drill results have recently been reported from the "Trend 1-Trend 2 Gap" at approximately 500 and 1,000 metres vertical depth, demonstrating continuity of mineralization across what were previously thought to be discrete mineralization trends (see Radisson news release dated June 1, 2026 and September 2, 2026).

The eight new drill holes at the Project reported today continue to demonstrate the very high incidence of intercepts with grades and thicknesses consistent with the Project's mineral resources ("hits", per Table 2). This now stands at 83% of all drill holes completed to date, an impressive result for a step-out drill program specifically targeting non-resource areas (Figure 4). Mineralization remains open in every direction, with clear opportunities to expand the quantity of new mineral resources, in particular by drilling at depth.

Figure 3: Vertical Section Through "O'Brien Mine East" with Today's New Drill Results

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Figure 4: Deep Step-Out Drill Holes Completed and/or Published by the Company Since March 2026

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Table 3: Detailed Assay Results Calculated at a 1 g/t Au Bottom Cut-Off from Drill Holes Published Today (see "Notes on Calculation of Drill Intercepts")

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Table 4: Drill Hole Collar Information for Drill Holes Published Today

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Notes: Hole lengths for wedges represent meterage from point of wedge. Collar position is reported for pilot hole.

QA/QC

All drill core in this campaign is NQ in size. Assays were completed on sawn half-core, with the second half retained in the core box for future reference. Geologists mark cut lines on the core perpendicular to the foliation. The half on the right side of the saw blade is bagged for the laboratory and the left half is retained as reference. Sample bags are sealed, placed in rice sacks, plastic-wrapped on pallets, and held in a secure facility until pick-up by the laboratory's dedicated truck.

Samples are delivered to MSALABS' analytical laboratory in Val-d'Or, Québec, for preparation and gold analysis. The entire sample is dried and crushed (70% passing a 2-millimetre sieve) and split to 500 g. Gold analysis is performed on an approximately 500 g aliquot (a single jar) using Chrysos PhotonAssay technology. Mineralized zones containing visible gold, plus additional intervals selected at the discretion of the logging geologist, are analyzed to extinction, whereby the entire sample is split into multiple ~500 g jars, each jar is analyzed by PhotonAssay, and the weighted average of the results is used for reporting. A one-metre sample typically requires five jars.

Certified reference materials (CRMs), blank samples, and reject duplicates are inserted for quality assurance and quality control. Either a CRM, a blank, or a duplicate is inserted during regular sampling at a rate of 1 per 25 samples, with the insertion rate increased for intervals selected for assay to extinction. Four different CRMs are in use with an appropriate range of certified grades suited for O'Brien mineralization. Jars of CRM material are stored at the laboratory and inserted into the sample stream as directed by Radisson. The CRMs were selected by Radisson in accordance with Chrysos Corporation's best-practice guidelines for PhotonAssay. Blanks consist of commercially obtained crushed quartzite known to be barren of gold. Samples returning results greater than 1 g/t Au are also fire assayed.

MSALABS operates under ISO/IEC 17025 accreditation, utilizing industry-standard QA/QC frameworks for gold analysis. Through the integration of blanks, duplicates, and CRMs into its workflow, the laboratory adheres to established benchmarks that ensure precise, reliable, and verifiable results.

QP Disclosure

Disclosure of a scientific or technical nature in this news release was prepared under the supervision of Mr. Richard Nieminen, P.Geo, (QC), a geological consultant for Radisson and a Qualified Person for purposes of NI 43-101. Mr. Luke Evans, M.Sc., P.Eng., ing, of SLR Consulting (Canada) Ltd., is the Qualified Person responsible for the preparation of the MRE at O'Brien. Each of Mr. Nieminen and Mr. Evans is independent of Radisson and the O'Brien Gold Project.

About Radisson Mining

Radisson is a gold exploration company focused on its 100% owned O'Brien Gold Project, located in the Bousquet-Cadillac mining camp along the world-renowned Larder-Lake-Cadillac Break in Abitibi, Québec. A July 2025 PEA described a low cost and high value project with an 11-year mine life and significant upside potential based on the use of existing regional infrastructure. Indicated Mineral Resources are estimated at 0.63 Moz (3.49 Mt at 5.59 g/t Au), with additional Inferred Mineral Resources estimated at 1.69 Moz (10.37 Mt at 5.08 g/t Au). Please see the NI 43-101 "O'Brien Gold Project Technical Report and Preliminary Economic Assessment, Québec, Canada" effective June 27, 2025, Radisson's news release dated March 2, 2026 "With Step-Out Drilling Continuing, Radisson Demonstrates Meaningful Resource Growth at O'Brien with an Updated Mineral Resource Estimate" and other filings made with Canadian securities regulatory authorities available at www.sedarplus.ca for further details and assumptions relating to the O'Brien Gold Project. For more information on Radisson, visit our website at www.radissonmining.com or contact:

Matt Manson
President and CEO
416.618.5885
mmanson@radissonmining.com

Kristina Pillon
Manager, Investor Relations
604.908.1695
kpillon@radissonmining.com

Forward-Looking Statements

This news release contains "forward-looking information" within the meaning of the applicable Canadian securities legislation that is based on expectations, estimates, projections, and interpretations as at the date of this news release. Forward-looking statements including, but are not limited to, statements with respect to the ability to execute the Company's plans relating to the O'Brien Gold Project as set out in the Preliminary Economic Assessment; the Company's ability to complete its planned exploration and development programs; the absence of adverse conditions at the O'Brien Gold Project; the absence of unforeseen operational delays; the absence of material delays in obtaining necessary permits; the price of gold remaining at levels that render the O'Brien Gold Project profitable; the Company's ability to continue raising necessary capital to finance its operations; the ability to realize on the mineral resource and mineral reserve estimates; assumptions regarding present and future business strategies; local and global geopolitical and economic conditions and the environment in which the Company operates and will operate in the future; planned and ongoing drilling; the significance of drill results; the ability to continue drilling; the impact of drilling on the definition of any resource; and the ability to incorporate new drilling in an updated technical report and resource modelling; the Company's ability to grow the O'Brien Gold Project; and the ability to convert inferred mineral resources to indicated mineral resources.

Any statement that involves discussions with respect to predictions, expectations, interpretations, beliefs, plans, projections, objectives, assumptions, future events or performance (often but not always using phrases such as "expects", or "does not expect", "is expected", "interpreted", "management's view", "anticipates" or "does not anticipate", "plans", "budget", "scheduled", "forecasts", "estimates", "believes" or "intends" or variations of such words and phrases or stating that certain actions, events or results "may" or "could", "would", "might" or "will" be taken to occur or be achieved) are not statements of historical fact and may be forward-looking information and are intended to identify forward-looking information. Except for statements of historical fact relating to the Company, certain information contained herein constitutes forward-looking statements. Forward-looking information is based on estimates of management of the Company, at the time it was made, involves known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of the companies to be materially different from any future results, performance or achievements expressed or implied by such forward-looking information. Such factors include, among others; the risk that the O'Brien Gold Project will never reach the production stage (including due to a lack of financing); the Company's capital requirements and access to funding; changes in legislation, regulations and accounting standards to which the Company is subject, including environmental, health and safety standards, and the impact of such legislation, regulations and standards on the Company's activities; price volatility and availability of commodities; instability in the global financial system; the effects of high inflation, such as higher commodity prices; the risk of any future litigation against the Company; changes in project parameters and/or economic assessments as plans continue to be refined; the risk that actual costs may exceed estimated costs; geological, mining and exploration technical problems; failure of plant, equipment or processes to operate as anticipated; accidents, labour disputes and other risks of the mining industry; delays in obtaining governmental approvals or financing; risks relating to the drill results at O'Brien; the significance of drill results; and the ability of drill results to accurately predict mineralization. Although the forward-looking information contained in this news release is based upon what management believes, or believed at the time, to be reasonable assumptions, the parties cannot assure shareholders and prospective purchasers of securities that actual results will be consistent with such forward-looking information, as there may be other factors that cause results not to be as anticipated, estimated or intended, and neither the Company nor any other person assumes responsibility for the accuracy and completeness of any such forward-looking information. The Company believes that this forward-looking information is based on reasonable assumptions, but no assurance can be given that these expectations will prove to be correct and such forward-looking statements included in this press release should not be unduly relied upon. The Company does not undertake, and assumes no obligation, to update or revise any such forward-looking statements or forward-looking information contained herein to reflect new events or circumstances, except as may be required by law. These statements speak only as of the date of this news release.

Please refer to the "Risks and Uncertainties Related to Exploration" and the "Risks Related to Financing and Development" sections of the Company's Management's Discussion and Analysis dated April 23, 2026 for the year ended December 31, 2025 available electronically on SEDAR+ at www.sedarplus.ca. All forward-looking statements contained in this press release are expressly qualified by this cautionary statement.

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.

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