Petersburg is a town in Lincoln and Marshall counties in the U.S. state of Tennessee.

U.S. Route 431 (US 431), which connects Petersburg with Lewisburg and Fayetteville, traverses the western part of town.

According to the United States Census Bureau, the town has a total area of 0.9 square miles (2.4 km2), all land.

As of the 2020 United States census, there were 528 people, 227 households, and 153 families residing in the town.

31.1% of all households were made up of individuals, and 15.7% had someone living alone who was 65 years of age or older.