Spartanburg County is a county located on the northwestern border of the U.S. state of South Carolina. As of the 2020 census, the population was 327,997, making it the fifth-most populous county in South Carolina. Its county seat is Spartanburg. Spartanburg County is the largest county within the Spartanburg, SC Metropolitan Statistical Area, which is also included in the Greenville-Spartanburg-Anderson, SC Combined Statistical Area.