Smithfield is a town in and the county seat of Johnston County, North Carolina, United States. As of the 2010 census the 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 approximately 30 miles (48 km) southeast of downtown Raleigh. The Raleigh-Durham-Cary Combined Statistical area has a population of over 2 million residents.
Smithfield was Johnston County's first town and second county seat. The town was started near Smith's ferry on the Neuse River. The county court house was moved from Hinton's Quarter to Smithfield in 1771. The town was first known as Johnston County Courthouse. It was incorporated as Smithfield in 1777.
The third North Carolina state legislature met in Smithfield in 1779 and 1780.
Smithfield is in central Johnston County and is bordered to the northeast by Selma.