Kaycee is a town in Johnson County, Wyoming, United States. The population was 247 at the 2020 census. It is home to a museum that preserves the cattle ranching heritage of the area, especially the history of the Johnson County War. Kaycee was incorporated in 1906 after the establishment of a small post office and general store. The town was named after the brand "KC" used by its earliest homesteader, John Nolan. The government required the name to be spelled out resulting in "Kaycee".