Austell is located along the southern border of Cobb County at 33°48′57″N 84°38′10″W / 33.81583°N 84.63611°W / 33.81583; -84.63611 (33.815905, −84.636242). A small portion of the city extends south into Douglas County. It is bordered by Lithia Springs to the south and Mableton to the east. The city of Powder Springs is 4 miles (6 km) to the northwest. U.S. Route 78 passes through the city, leading east 15 miles (24 km) to downtown Atlanta and west 8 miles (13 km) to Douglasville.

The area that is now Austell was frequented by game hunters and trappers on their way to the area's salt licks. These early visitors claimed the area's waters had medicinal properties. It soon became a destination for therapeutic healing, leading to the founding of a town known as Salt Springs. As immigration increased and demand for land near the spring grew, G. O. Mozely donated and subdivided 40 acres (16 ha) of his land, enhancing the loose settlement with a street plan. Later, the spring was renamed Lithia Springs due to the water containing lithium carbonate, and the neighboring city of Lithia Springs was founded in 1882. In 1888, the lithia spring water was bottled and sold under the commercial name Bowden Lithia Spring Water. The historic lithia spring water is still bottled and sold under the name brand Lithia Spring Water. The Georgia Pacific Railway chose the town of Austell to be a station depot, being the dividing point for the major Birmingham and Chattanooga railway lines.

When someday comes you'll need to get in.

When someday comes you'll need to be able to get around.