It was back to back titles for Rockwell at Thomond Park, when the Tipperary school held out for the narrowest of victories.
In a hard fought opening half Munchin's opened the scoring with a try from wing forward Matthew McSweeney ten minutes before the interval to give his side a 5-0 interval lead.
Aidan Moynihan hit back with two early second half penslties.
Munchin's hit back and pounded the Rockwell line but the Tipperary defence held firm. Munchin's cause was not helped by indiscipline.
Rockwell eventually lifted the siege and spent the final five minutes camped in the Munchin's Twenty Two as they wound down the clock.
Rockwell winger Steve McMahon was voted man of the match
Scorers Rockwell College: Aidan Moynihan 2 pens.
St. Munchin's College: Matthew McSweeney try,
Rockwell: David Johnston; Alex Lynch, Rob Jermyn, Cillian Kiely, Steve McMahon; Aidan Moynihan, Dylan McGagh; Jack McCormack, Darragh Mulcahy, James Maxwell; Sean McCarthy (capt), Darragh Foley; Aaron Sweeney, Sonny O'Dwyer, Aidan Butler.
Replacements: Sean McNulty, Robbie Lyons, William O'Dwyer, Neville Flynn, James Feehan, Aidan Barron, Sean O'Donoghue, Ronan Maher.
St. Munchin's College: Cormac O'Donnell; Edward O'Keeffe, Dan Goggin, Tom O'Neill, James Clancy; Shane Airey, Ben Nugent; Eoghan Kelly, Luke O'Halloran, Evan Ryan; Gavin Ryan, Ezra Nugent; Matthew McSweeney, Darren Ryan, Lee Nicholas (capt).
Replacements: Shane Houlihan, Daithi O'Byrne, Daniel Montgomery, Ger Powell, Ryan Tsang, Diarmuid Morrissey, Shane O'Mullan, Gary Bateman.
Referee: Leo Colgan (MAR)