Smithfield is a borough in Fayette County, Pennsylvania, United States. The population was 830 at the 2020 census. It is served by the Albert Gallatin Area School District. The town's largest employer is a small wire producing plant run by Nelson Steel.

Fayette County is a county in the Commonwealth of Pennsylvania. It is located in southwestern Pennsylvania, adjacent to Maryland and West Virginia. As of the 2020 census, the population was 128,804. Its county seat is Uniontown. The county was created on September 26, 1783, from part of Westmoreland County and named after the Marquis de Lafayette. The county is part of the Southwest Pennsylvania region of the state.