Tries from Chris Farrell, Stuart McCloskey, Finlay Bealham, Josh van der Flier and Jacob Stockdale helped to steer the hosts to a 39-31 win. Returning out-half Joey Carbery kicked 14 points.
The Vodafone Summer Series opener had 3,000 supporters present at the Aviva Stadium, as part of a test pilot programme for the safe return of supporters to outdoor sporting events.