McCarron's touchdown toss with 3:15 remaining erased a 28-25 deficit and handed Alabama (12-1, 7-1 SEC) a victory in the SEC championship game.
The defending national champion Crimson Tide now advance to their third title game in four years. They will take on top-ranked Notre Dame Jan. 7 in Miami for the NCAA crown.
The game was back-and-forth in the second half with four lead changes.
The Bulldogs (11-2, 7-1) had one last chance after Alabama's decisive score, with quarterback Aaron Murray driving them 78 yards to the Crimson Tide's 8-yard line with seconds remaining.
But his short pass to Chris Conley was 5 yards shy of the goal line as time expired, and Georgia's hopes for a first national title since 1980 evaporated.
McCarron finished 13-of-21 for 162 passing yards with an interception. Eddie Lacy rushed for 181 yards and two scores on 20 carries for Alabama.
Murray completed 18-of-33 passes for 265 yards, one TD and one interception for the Bulldogs.
Todd Gurley racked up 122 yards and scored twice on 23 carries for Georgia.