Hernando is the county seat of DeSoto County, on the northwestern border of Mississippi, United States. The population was 17,138 according t…Hernando is the county seat of DeSoto County, on the northwestern border of Mississippi, United States. The population was 17,138 according to the 2020 census records. It is located on the south side of the Memphis, Tennessee metro area. U.S. Route 51 and the I-55 freeway traverse the city from north to south, and the I-69 freeway crosses the city from east to west. The county courthouse is located within Hernando's historic downtown square. It is located at the intersection of Commerce Street and present-day U.S. 51.