Kemper County is a county located in the U.S. state of Mississippi. As of the 2010 census, the population was 10,456. Its county seat is De Kalb. The county is named in honor of Reuben Kemper.The county is part of the Meridian, MS Micropolitan Statistical Area.United States Senator John C. Stennis, who served from 1947 to 1988, was born in Kemper County.