Shelbourne 0 Longford Town 1
Rob Manley missed a penalty before scoring the goal that fired Longford Town deservedly back to the Premier Division for the first time since 2016.
Having to play for over an hour with 10 men, Shelbourne's season duly imploded at Richmond Park.
Dumped out of the FAI Cup by Athlone Town, who finished second bottom of the First Division, a fortnight ago, this marked a shocking end to the Drumcondra side's season with an immediate return to the First Division.
Missing the drive of their suspended skipper Gary Deegan, Shelbourne struggled to impose themselves on the play as Longford started confidently, passing the ball well.
But a slow burner of a game didn’t spark to life until the 25th minute.
Racing on to a Karl Chambers' ball over the top, Longford striker Manley was nudged to the ground by Shelbourne captain Luke Byrne to win a penalty.
Booked just two minutes earlier, also for a foul on Manley, Byrne, only back following a suspension, was shown a second yellow card and sent off.
There was a reprieve of sorts for Shelbourne, as Longford top scorer Manley blazed his spot kick wastefully over the bar.
Manley made amends, though, as Longford’s continued dominance told nine minutes into the second half.
His defender brother Joe threaded a ball forward through midfield to Dylan Grimes. He helped it on for the run of Manley who shot to the net with the help of a deflection off Dan Byrne for his 10th goal of the season.
Longford thought they had doubled their lead three minutes later when Joe Gorman forced the ball home following a goalmouth scrabble, but referee Neil Doyle disallowed it.
Shelbourne pressed hard as they chased the game late on. But substitute Ryan Brennan hooked over the bar from an Alex O'Hanlon cross before working Lee Steacy in the Longford goal a minute from time was as much as they could muster.
"This is a culmination of all the hard work we've put in," said Longford manager Daire Doyle.
“We’ve achieved a special promotion. That’s the feeling in this group of what’s happened and how we got it.
“The dramatic stuff at UCD, the controlled performance against Galway and we came here against Shelbourne and I thought we played the football when it was there to be played.
“But one huge thing we had there in the second half was how much we were prepared to work for each other, help each other and fight for each other. That’s what won us the game.
“We’re fully deserving of where we’ve ended up. I’m delighted. I’m over the moon. It’s a great feeling.”
Shelbourne: Brady; Friel, L. Byrne, O. Brennan, O'Hanlon; Quinn, M. Byrne (McManus, 58); Sheppard (Brennan, 58), Farrell (D. Byrne, 28), Rooney (Dobbs, 58); Kilduff (Kabia, 64).
Longford Town: Steacy; McDonnell, Gorman, J. Manley; Elworthy, Zambra, Dervin, McNally; Chambers, (Byrne, 69), Grimes; R. Manley (Warfield, 89).
Referee: Neil Doyle (Dublin).