Johnston County is a county located in the U.S. state of North Carolina. As of the 2020 census, the population was 215,999. Its county seat is Smithfield.

Smithfield is a town in and the county seat of Johnston County, North Carolina, United States. As of the 2010 census, its population was 10,966, and in 2019 the estimated population was 12,985. Smithfield is home to the Ava Gardner Museum and is situated along the Neuse River, where visitors enjoy the annual Smithfield Ham and Yam Festival, walks along the Buffalo Creek Greenway, and the historic downtown district. The town is located near North Carolina's Research Triangle and is about 30 miles (48 km) southeast of downtown Raleigh. The Raleigh-Durham-Cary combined statistical area has a population over 2 million residents.