Douglasville police didn't immediately identify the woman or release details on how investigators took her into custody.
The woman was driving a black sedan eastbound on I-20 around 4:40 p.m. Sunday when the shooting occurred, the Douglasville police said. She was believed to have come from the Carrollton area.
The woman took the exit at Chapel Hill Road after drawing a gun and shooting a 17-year-old in the face, FOX5 Atlanta reported, citing police.
The teen was rushed to a nearby hospital and is expected to survive, the station reported.
Douglasville police offered a $5,000 reward for information that leads to an arrest.
Authorities asked anyone with information about the incident to contact Detective Sean Williams at 678-293-1747.
Douglasville is located about 23 miles west of Atlanta.