Buffalo County is a county located in the U.S. state of Nebraska in the Midwestern United States. As of the 2020 United States Census, the population was 50,084, making it Nebraska's fifth-most populous county. Its county seat is Kearney. The county was created in 1855 and was organized in 1870. It was named after the once-prevalent bison herds of the Great Plains. Buffalo County is part of the Kearney Micropolitan Statistical Area.