Indicate by check mark whether the registrant
files or will file annual reports under cover of Form 20-F or Form 40-F.
Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.
Exhibit 99.1

Cat Lake First Nation and First Mining Gold Reach
Milestone Agreement on Mobilizing the Cat Lake All-Season Access Road
TREATY 9 TERRITORY, ON, June 16, 2026 /CNW/ - Cat
Lake First Nation ("CLFN") and First Mining Gold Corp. ("First Mining" or the "Company")
(TSX: FF) (OTCQX: FFMGF) (FRANKFURT: FMG) have finalized a landmark agreement to mobilize development of an all-season access road to
Cat Lake First Nation in northwestern Ontario.
The route connecting Cat Lake First Nation to Sioux
Lookout via the Vermilion River Road will utilize a mix of existing forestry roads and new construction to minimize costs while maximizing
transportation and regional socio-economic benefits.
With this infrastructure agreement, First Mining has
committed up to $4 million to directly fund road permitting, right-of-way clearing, geotechnical fieldwork, and detailed engineering design
to start in summer 2026.
This access road has long been a key priority for
Cat Lake First Nation, as outlined in their Band Council Resolution on May 26, 2026. The project has received vital, collaborative support
from the Impact Assessment Agency of Canada ("IAAC"), while the role of Ontario is unclear.
"My mandate as Chief was to establish an all-season
road that ends decades of isolation, improves safety and healthcare, and lowers living costs. This infrastructure is a major socio-economic
win for both Cat Lake and the entire region," observed Chief Russell Wesley of Cat Lake First Nation. "First Mining
Gold management has shown true partnership by putting real money on the table to start engineering, and the federal IAAC continues to
cooperate constructively."
"Reaching this agreement with Cat Lake First
Nation is a definitive step forward for the development of the Springpole Gold Project," stated Dan Wilton, CEO of First
Mining Gold Corp. "Year-round infrastructure is vital to the project's long-term viability and ensures that economic benefits
are shared within the local community. We are grateful for the leadership and efforts of the Chief and Council of Cat Lake First Nation."
The agreement coordinates directly with the joint
position authorizing the Springpole Project announced by Cat Lake and Lac Seul First Nations, ensuring all corridor activities adhere
strictly to the 35 cultural and ecological conditions derived from the historic, Anishinaabe-led Impact Assessment ("ALIA").
Ontario is the final crucial partner required to fully unlock this corridor.
About Cat Lake First Nation
ᐱᔕᐤ
ᓴᑲᐦᐃᑲᐣ (Bizhiw-zaaga'igan) or Cat Lake First Nation is a remote Anishinaabe community located
approximately 180 kilometers north of Sioux Lookout in Northwestern Ontario. As a fly-in community, Cat Lake is home to 650+ residents
living on-reserve. The community remains disconnected from all-season provincial road networks, relying instead on air travel and a limited
seasonal ice road only accessible for a short period (January to early March) most years. Today, Cat Lake remains a vibrant community
that honors its traditions of harvesting and fishing--while leading the way in modern health and sustainability initiatives to protect
its heritage and support its future generations.
About First Mining Gold Corp.
First Mining is a gold developer advancing two of
the largest gold projects in Canada, the Springpole Gold Project in northwestern Ontario, where permitting activities are on-going with
a final Environmental Impact Statement / Environmental Assessment for the project submitted in November 2024, and the Duparquet Gold Project
in Quebec, a PEA-stage development project located on the Destor-Porcupine Fault Zone in the prolific Abitibi region. First Mining also
owns a 20% project interest in the Pickle Crow Gold Project and large equity interest in Seva Mining Corp.
First Mining was established in 2015 by Mr. Keith
Neumeyer, founder and CEO of First Majestic Silver Corp.
ON BEHALF OF FIRST MINING GOLD CORP.
Daniel W. Wilton
Chief Executive Officer and Director
Cautionary Note Regarding Forward-Looking Statements
This news release includes certain "forward-looking
information" and "forward-looking statements" (collectively "forward-looking statements") within the meaning
of applicable Canadian and United States securities legislation including the United States Private Securities Litigation Reform Act of
1995. These forward-looking statements are made as of the date of this news release. Forward-looking statements are frequently, but not
always, identified by words such as "expects", "anticipates", "believes", "plans", "projects",
"intends", "estimates", "envisages", "potential", "possible", "strategy",
"goals", "opportunities", "objectives", or variations thereof or stating that certain actions, events or
results "may", "could", "would", "might" or "will" be taken, occur or be achieved, or
the negative of any of these terms and similar expressions.
Forward-looking statements in this news release
relate to future events or future performance and reflect current estimates, predictions, expectations or beliefs regarding future events
and include, but are not limited to, statements with respect to (i) funding commitment for the Cat Lake First Nation all season access
road; (ii) timing of the start of the project; (ii) completing permitting and feasibility study at the Springpole Project; and (iv) First
Mining's plans related to its Springpole, Duparquet and other projects. All forward-looking statements are based on First
Mining's or its consultants' current beliefs as well as various assumptions made by them and information currently available to them.
There can be no assurance that such statements will prove to be accurate, and actual results and future events could differ materially
from those anticipated in such statements. Forward-looking statements reflect the beliefs, opinions and projections on the date the statements
are made and are based upon a number of assumptions and estimates that, while considered reasonable by the respective parties, are inherently
subject to significant business, economic, competitive, political and social uncertainties and contingencies. Such factors include, without
limitation the Company's business, operations and financial condition potentially being materially adversely affected by the outbreak
of epidemics, pandemics or other health crises, and by reactions by government and private actors to such outbreaks; risks to employee
health and safety as a result of the outbreak of epidemics, pandemics or other health crises, that may result in a slowdown or temporary
suspension of operations at some or all of the Company's mineral properties as well as its head office; fluctuations in the
spot and forward price of gold, silver, base metals or certain other commodities; fluctuations in the currency markets (such as the Canadian
dollar versus the U.S. dollar); changes in national and local government, legislation, taxation, controls, regulations and political or
economic developments; risks and hazards associated with the business of mineral exploration, development and mining (including environmental
hazards, industrial accidents, unusual or unexpected formations, pressures, cave-ins and flooding); the presence of laws and regulations
that may impose restrictions on mining; employee relations; relationships with and claims by local communities, indigenous populations
and other stakeholders; availability and increasing costs associated with mining inputs and labour; the speculative nature of mineral
exploration and development; title to properties.; and the additional risks described in the Company's Annual Information Form for the
year ended December 31, 2025 filed with the Canadian securities regulatory authorities under the Company's SEDAR+ profile at www.sedarplus.ca,
and in the Company's Annual Report on Form 40-F filed with the SEC on EDGAR.
First Mining cautions that the foregoing list of
factors that may affect future results is not exhaustive. When relying on our forward-looking statements to make decisions with respect
to First Mining, investors and others should carefully consider the foregoing factors and other uncertainties and potential events. First
Mining does not undertake to update any forward-looking statement, whether written or oral, that may be made from time to time by the
Company or on our behalf, except as required by law.
Cautionary Note to United States Investors
The Company is a "foreign private issuer"
as defined in Rule 3b-4 under the United States Securities Exchange Act of 1934, as amended, and is eligible to rely upon the Canada-U.S.
Multi-Jurisdictional Disclosure System, and is therefore permitted to prepare the technical information contained herein in accordance
with the requirements of the securities laws in effect in Canada, which differ from the requirements of the securities laws currently
in effect in the United States. Accordingly, information concerning mineral deposits set forth herein may not be comparable with information
made public by companies that report in accordance with U.S. standards.
Technical disclosure contained in this news release
has not been prepared in accordance with the requirements of United States securities laws and uses terms that comply with reporting standards
in Canada with certain estimates prepared in accordance with NI 43-101.
NI 43-101 is a rule developed by the Canadian
Securities Administrators that establishes standards for all public disclosure an issuer makes of scientific and technical information
concerning the issuer's material mineral projects.
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SOURCE First Mining Gold Corp.
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For further information: For further information, please contact:
Toll Free: 1 844 306 8827 | Email: info@firstmininggold.com; Paul Morris | Director, Investor Relations | Email: paul@firstmininggold.com
CO: First Mining Gold Corp.
CNW 07:30e 16-JUN-26