Cheyenne Pierce, 17, was thrown from the vehicle and killed, the State Patrol said.
The surviving passenger, 18-year-old Demetrius Roberts, was taken to Grady Memorial Hospital, but his condition was unknown.
Both are from Union City, authorities said.
Troopers investigating the wreck closed the two left lanes on southbound I-85 for roughly two hours on Sunday, authorities said.
Union City Police officials could not be reached Sunday for comment.