Johnson, a six-time Cup champion, started near the back after failing to get in a qualifying run because of inspection issues. But the No. 48 Chevrolet was the fastest car on the track at the end of the weekend, cruising across the finish line a comfortable 1.803 seconds ahead of Kevin Harvick.
It was the 71st victory of Johnson's career, and his fourth at the 1.54-mile trioval south of Atlanta.
Dale Earnhardt Jr. was third, followed by Daytona 500 winner Joey Logano.
