The score came after Tannehill led the Dolphins on a 13-play drive following a missed 34-yard field-goal try by Atlanta's Matt Bryant with 4:46 to play.
The Miami quarterback passed for 236 yards (24-of-35) with one interception as the Dolphins (3-0) erased a pair of 10-point deficits and notched a third straight win to open the season for the first time since 2002.
Matt Ryan made good on 23-of-38 pass attempts for 231 yards and two touchdowns for the Falcons (2-1).
Nativity scenes to be moved at Guantanamo after troops' protest
S. Carolina GOP Governor Nikki Haley breaks wood with hands [VIDEO]