Osceola is a city in St. Clair County, Missouri, United States. The population was 835 at the 2000 census. It is the county seat of St. Clair County. The town was the site of the September 1861 Sacking of Osceola by Jayhawkers in which the town was burned and its courthouse looted. The event inspired the 1976 Clint Eastwood film The Outlaw Josey Wales.
Osceola is located at 38°2′47″N 93°41′58″W / 38.04639°N 93.69944°W / 38.04639; -93.69944 (38.046427, -93.699512). According to the United States Census Bureau, the city has a total area of 0.9 square miles (2.5 km²), of which, 0.9 square miles (2.4 km²) of it is land and 0.04 square miles (0.1 km²) of it (2.11%) is water.
As of the census of 2000, there were 835 people, 373 households, and 207 families residing in the city. The population density was 896.1 people per square mile (346.7/km²). There were 472 housing units at an average density of 506.5 per square mile (196.0/km²). The racial makeup of the city was 97.37% White, 0.36% African American, 0.60% Native American, 0.24% Asian, 0.12% Pacific Islander, 0.48% from other races, and 0.84% from two or more races. Hispanic or Latino of any race were 1.08% of the population.