Flynn shook off snow and arctic temperatures at Lambeau Field to pass for 258 yards and a touchdown while subbing for the injured Aaron Rodgers, sparking Green Bay to its first win since its star quarterback's collarbone injury.
Flynn completed 24-of-32 passes -- including a 2-yard TD toss to Andrew Quarless with 12:01 remaining -- and an interception as the Packers (6-6-1) stayed alive in their quest for an NFC North title.
Quarless picked up 66 yards on six catches and Eddie Lacy contributed 65 rushing yards with a touchdown on 20 carries as Green Bay broke a five-game winless streak.
Atlanta (3-10) fell as Matt Ryan was turned the ball over on a pick-off and a fumble. He passed for 206 and a pair of touchdowns on a 20-of-35 efficiency.