Alexandria is a town in DeKalb County, Tennessee, United States.

U.S. Route 70 (Nashville Highway) passes through the southwest side of the town, leading northwest 18 miles (29 km) to Lebanon and southeast 17 miles (27 km) to Smithville, the DeKalb County seat.

Tennessee State Route 53 passes just east of the town, leading north 7 miles (11 km) to Interstate 40 at New Middleton.

According to the United States Census Bureau, the town has a total area of 2.0 square miles (5.2 km2), all of it land.

As of the 2020 United States census, there were 981 people, 397 households, and 269 families residing in the town.