Marist College bridged a 35-year gap when they captured the title for the second time in their history with a decisive victory at the Sportsground yesterday.
The win completes a league and cup double for the Athlone school who were beaten in the 2007 and '08 finals and whose only other appearance in a final saw them defeat Sligo Grammar in the 1977 decider.
Marist laid the foundation for the victory in the opening half when back-row brothers Brian and Kevin Cooper got over for tries.
Sligo kept fighting but were unable to prevent a second successive final defeat and they have now lost six of the last nine deciders.
They almost took the lead when Colm Egan, brother of Westlife's Kian, was narrowly off target with a penalty from 43 metres into the wind.
But Marist quickly got on top and their pressure yielded results as Brian Cooper displaying a neat step to break through and score on 11 minutes.
Ben Carty was off target with the conversion but he made no mistake in making it 12-0 seven minutes from the break after Kevin Cooper finished off a fine move to touch down.
Egan was off target with penalty opportunities either side of the break as Sligo refused to lie down.
But the Marist defence was excellent in repelling the waves of Sligo attacks, with skipper Robbie Henshaw inspirational.
"We learned a lot from the defeats in the final in 2007 and '08," said Marist coach Mick Loftus.
Marist COLLEGE -- C Seery; H Hughes, R Henshaw, R Sheridan, E O'Reilly; B Carty, R Ashe; B Teape, E Kelly, S Meunargia; N Carr (S Dempsey 42), C White; D Lynch (S Chitsatso 63), B Cooper, K Cooper.
Sligo Grammar -- C Egan; D Higgins, J McGoldrick (P Deering 42), M Martin, C Cooper; M Green (P Maloney 38), E Gavin; E Kilroy, Martin Davey, Matthew Davey; R Hehir (P Britten 42); D O'Dowd-Hill; S Boyle, S Mullaney, T Ferrari.
Ref -- D Collins (CBIRFU).