Alloa beat Forfar 3-0 at the Indodrill Stadium on Sunday evening to retain their Championship status for another year.
Dick Campbell's men led 3-1 from the first leg at Station Park in midweek and were bidding to return to the second tier for the first time since 1991/92 but missed out in a dramatic 90 minutes.
The visitors looked comfortable in the first half but fell behind just before the break when Michael Chopra beat keeper Rab Douglas with a fine finish.
A defensive mix-up allowed Liam Buchanan to level the aggregate score midway through the second half but Danny Lennon's team then had substitute Graeme Holmes sent off for a bad tackle on Omar Kader, who was breaking down the right.
Extra time was looming but, with six minutes left, defender Daryll Meggatt headed in the winner from a corner as Alloa completed a stirring comeback.