Pratt County is a county located in the U.S. state of Kansas. Its county seat and largest city is Pratt. As of the 2020 census, the county population was 9,157. The county was named for Caleb Pratt, a U.S. soldier who died in the Battle of Wilson's Creek during the American Civil War and had previously been involved in Bleeding Kansas. The county consists overwhelmingly of prairie and contains few watercourses; the most important of these is the Ninnescah River.