Cayce is a city in the U.S. state of South Carolina, along the Congaree River. Its population was 12,528 at the 2010 census and rose to 13,789 in the 2020 United States Census, and it is the third-most populated municipality in Lexington County. The city is primarily in Lexington County, with additional, predominantly rural land to the east in Richland County. Cayce is part of the Columbia metropolitan statistical area and is within South Carolina's Midlands region.