Four first half goals on a wind-swept AUL Complex pitch were enough to see the Under 21s start their Dr Tony O'Neill League campaign off with a comfortable win.
Anto Flood slotted home the first on the near post on 18 minutes following a through ball from Luke Fitzpatrick.
Just two minutes later Flood was brought down in the penalty box, Alan Reilly slotting home the spot kick for number two.
On 27 minutes, Fitzpatrick picked up the ball on the right wing, cut inside and unleashed an unstoppable shot from the edge of the box.
Lee Roche finished off the Saints scoring on 37 minutes.
With nine minutes left in the game Dublin University got a consolation with a sweet free kick from just outside the edge of the box.
First team players, Colm Foley, Stephen Caffrey and Alan Reilly all took part in the fixture as part of their recouperation from injuries and came through unscathed.
Team: Clarke, Moore, Pearson, Caffrey, Foley, Rooney, Fitzpatrick, Roche, Flood, Haverty, Reilly. Subs: Fagan for Reilly (57 mins), Foran for Caffrey (57 mins), McInerney for Clarke (65 mins)