Shelbourne 1 Treaty United 0
Georgie Poynton was the toast of Tolka Park as his 74th minute penalty sealed Shelbourne's immediate return to the Premier Division.
It brought redemption at the first time of asking for Ian Morris’s side, they’ve suffered just one defeat in their 24 games to date ending the hurt of last year’s unlikely relegation.
It was Shelbourne’s first win of the season over a spirited Treaty who remain well on course to make the play-offs in their debut season in the league.
In an utterly dominant first half, Shelbourne just couldn’t muster the lead, hitting the woodwork and also having a goal disallowed.
Wingers Yassine En-Neyah and Shane Farrell were lively and inventive, the former setting up John Ross Wilson to see his drive deflected away by Stephen Cristopher for one of eight corners to the home side before the break.
Treaty goalkeeper Tadhg Ryan made a double save from Ryan Brennan and En-Neyah before Farrell, with a dipping volley, and Poynton, with a drive from distance, weren't far off target.
Maintaining the onslaught, defender Ally Gilchrist powered a 38th minute header from Kevin O'Connor's corner against the back post.
The ball was in the Treaty net from another O’Connor corner minutes later, but the goal was disallowed for a foul on the overworked goalkeeper.
Though Shelbourne continued to own much of the ball into the second half, they had goalkeeper Brendan Clarke to thank on 63 minutes. Marc Ludden's low cross was deflected to the well-placed Matt Keane whose powerful drive was brilliantly tipped over the top by the veteran keeper.
Having survived that drama at their end, it soon arrived at the other to seal victory and the title.
Clyde O’Connell was a little too touch-tight to Farrell as he pulled the Shels man as he controlled Kevin O’Connor cross.
Referee Alan Patchell pointed to the spot with Poynton scoring emphatically from 12 yards.
Shelbourne: Clarke; Wilson, Byrne, Gilchrist, Ledwidge (McManus, 66); Poynton, K O'Connor; Farrell, Brennan, En-Neyah (Rooney, 84); M. O'Connor
Treaty United: Ryan; Fleming, Walsh, O'Donnell, Ludden; MaNamara, O'Connell (George, 85); Keane (Coustrain, 80), McSweeney (Hanlon, h-t), Christopher; Melody (Armshaw, 80).
Referee: Alan Patchell (Dublin).