Muonio is a municipality located in the Lapland region of northern Finland. Situated above the Arctic Circle, the town is positioned within the Fell Lapland subregion and lies along the country's western border with Sweden, which is defined by the Muonio River.
The area is characterized by its location in the fell region. The nearest Finnish municipalities are Enontekiö to the north, Kittilä to the east, and Kolari to the south. A road bridge crosses the Muonio River to the southwest, connecting the town to the Swedish hamlet of Muoniovaara in the Pajala Municipality.