Shelbourne toasted their First Division title success with a 7-0 hammering of Limerick in front of a rammed Tolka Park.
Shels clinched the league with a 3-1 victory at their nearest challengers Drogheda United last week, so it was party time on their own patch in the last game of the campaign.
Jaze Kabia bagged a hat-trick, Conan Byrne scored twice with Shane Farrell, Oscar Brennan and Aidan Friel completing the scoring.
The Drogs have finished second on goal difference despite going down 4-1 at Bray Wanderers. Dean Williams (2) and Dylan McGlade gave the Seagulls a 3-0 half-time lead, and though Chris Lyons pulled one back on 50 minutes, McGlade struck again at the death to wrap it up.
Longford Town, who won 3-1 at Cobh, will play Cabinteely in the third-fourth placed play-off.
Cabinteely finished their regular season with a 2-1 defeat of Wexford.
The winners of that tie will then face Drogheda. Whoever emerges from that takes on the team that finishes second-bottom of the Premier Division in a relegation/promotion shootout.