Lanett, originally called Bluffton, is located in eastern Alabama, on the Chattahoochee River, southwest of Atlanta.

The city's name is derived from Lafayette Lanier and Theodore Bennett, founders of the West Point Manufacturing Company.

[3] Its eastern boundary is the Alabama–Georgia state line, with the town of West Point, Georgia, bordering Lanett to the east.

Interstate 85 forms the southeast boundary of Lanett, with the city of Valley, Alabama, on the other side of the highway.

The Chattahoochee River forms the state line and eastern boundary of Lanett from I-85 north to the downtown area, at which point the state line turns north-northwest and becomes a land boundary between Lanett and West Point, Georgia.