Owatonna is a city in Steele County, Minnesota, United States. The population was 22,434 at the 2000 census. It is the county seat of Steele County. Owatonna is home to the Steele County Fairgrounds, which hosts the Steele County Free Fair in August. Interstate 35 and U.S. Routes 14, and 218 are three of the main arterial routes in the city.