Wilson's Mills is a town in Johnston County, North Carolina, United States. In 2010, the population was 2,277, up from 1,291 in 2000. As of 2018, the estimated population was 2,689. Wilson's Mills is located in north-central Johnston County. It is 6 miles north of Smithfield, the county seat. U.S. Route 70 passes through the southern side of the town, leading north…Wilson's Mills is a town in Johnston County, North Carolina, United States. In 2010, the population was 2,277, up from 1,291 in 2000. As of 2018, the estimated population was 2,689. Wilson's Mills is located in north-central Johnston County. It is 6 miles north of Smithfield, the county seat. U.S. Route 70 passes through the southern side of the town, leading northwest 26 miles to Raleigh and southeast 6 miles to Interstate 95 at Selma.