Colleton County is a county in the Lowcountry region of the U.S. state of South Carolina. As of the 2020 census, the population was 38,604. Its county seat is Walterboro. The county is named after Sir John Colleton, 1st Baronet, one of the eight Lords Proprietor of the Province of Carolina. After two previous incarnations, the current Colleton County was created in 1800.