Smithfield is a borough in Fayette County, Pennsylvania, United States.

The town's largest employer is a small wire-producing plant run by Nelson Steel.

[3] According to the United States Census Bureau, the borough has a total area of 0.71 square miles (1.84 km2), all land.

The racial makeup of the borough was 99.65% White, 0.23% African American and 0.12% Pacific Islander.

32.8% of all households were made up of individuals, and 17.6% had someone living alone who was 65 years of age or older.