Sunderland will face Wycombe for a place in the Championship after Patrick Roberts' 93rd-minute goal sent them to the League One play-off final courtesy of a 1-1 draw at Sheffield Wednesday.
Lee Gregory seized on Marvin Johnson's cross to fire in from close range and send the home fans wild by levelling the semi-final in the 74th minute.
The Black Cats, who had arrived with a 1-0 lead from the first leg, sealed a trip to Wembley shortly into 10 minutes of added time.
Jack Clarke found space on the left and supplied Roberts in front of goal, who slotted in to put Alex Neil's side into the final on May 21.