Dan Ballard headed in a 122nd-minute winner as Sunderland saw off Coventry City to reach the Championship playoff.
The header which came with the last touch of extra time, saw the hosts draw level on the night, but win on aggregate.
Sunderland had won 2-1 at Coventry last week.
Ephron Mason-Clark side-footed home in the second half of the semi-final second leg, taking the tie to extra-time.
With a penalty shoot-out looming Ballard struck from a corner, to send fans inside the Stadium of Light into ecstacy.
Sunderland now play Sheffield United in the final at Wembley on May 24.
The Blades made history in thrashing Bristol City 6-0 on aggregate in the other semi-final.
