Shawnee County is located in northeast Kansas, in the central United States. Its county seat and most populous city is Topeka, the state capital. As of the 2020 census, the population was 178,909, making it the third-most populous county in Kansas. The county was one of the original 33 counties created by the first territorial legislature in 1855, and it was named for the Shawnee tribe.

Topeka is the capital city of the U.S. state of Kansas and the seat of Shawnee County. It is along the Kansas River in the central part of Shawnee County, in northeast Kansas, in the Central United States. As of the 2020 census, the population of the city was 126,587. The Topeka metropolitan statistical area, which includes Shawnee, Jackson, Jefferson, Osage, and Wabaunsee Counties, had a population of 233,870 in the 2010 census.