South Mills is an unincorporated community and census-designated place in Camden County, North Carolina, United States. Its population was 454 as of the 2010 census. South Mills has a post office with ZIP code 27976, which opened on March 2, 1840. The community is located near U.S. Route 17, and U.S. Route 17 Business and North Carolina Highway 343, and future Interstate 87 pass through the community. The community derived its name from a watermill which operated near the original town site.