Irish were just 12 minutes away from becoming only the second team to beat Munster in a Heineken Cup tie at Thomond Park.
Their captain Seilala Mapusua scored a try and set up the second for Sailosi Tagicakibau as the visitors edged into a 14-7 lead, after a scoreless first half.
But Munster, who are Amlin Challenge Cup-bound now, hit back decisively with late tries from Niall Ronan, Keith Earls and replacement Darragh Hurley.
That closing barrage of points put a gloss on the final scoreline, but Munster can take heart from how they raised their game when staring at a possible third pool defeat.
Smarting from their Toulon nightmare, Munster made a sprightly start in heavy underfoot conditions, getting Johne Murphy and Denis Hurley involved early on.
Mapusua, in his final Heineken Cup outing for Irish, announced himself with a typical midfield burst, and Munster were unable to convert their early territory into points.
A solid lineout platform and some clever kicking from Darren Allinson brought the visitors forward, but they were hampered by prop Faan Rautenbach's sin-binning for stamping on David Wallace at a ruck.