Smithfield is located at 36°56'11" North, 81°58'0" West (36.936389, -81.966667).
According to the United States Census Bureau, the town has a total area of 10.45 mi2 (27.06 km2). 9.53 mi2 (24.68 km2) of it is land and 0.92 mi2 (2.39 km2) of it is covered by water. The total area is 8.82% water.
Smithfield is located in the Eastern Standard Time (EST) timezone, GMT-05:00. It observes Daylight Saving Time (DST).