Fairmont is a city in Martin County, Minnesota, United States. The population was 10,666 at the 2010 census. It is the county seat of Martin County.
According to the United States Census Bureau, the city has a total area of 16.5 square miles (42.8 km²), of which, 14.6 square miles (37.7 km²) of it is land and 2.0 square miles (5.1 km²) of it (11.86%) is water. The city of Fairmont itself has been built around a chain of five lakes: Lake George, Sisseton Lake, Budd Lake, Hall Lake, and Amber Lake. All except Amber Lake are connected by channels and are used extensively for recreational boating and fishing. Interstate 90 and Minnesota State Highway 15 are two of the main routes in the city.
As of the census of 2000, there were 10,889 people and 2,962 families residing in the city. The population density was 747.5 people per square mile (288.6/km²). There were 5,036 housing units at an average density of 345.7 per square mile (133.5/km²). The racial makeup of the city was 96.1% White, 0.4% African American, 0.1% Native American, 0.6% Asian, 0.03% Pacific Islander, 1.9% from other races, and 0.9% from two or more races.