Leinster became the first side to win three consecutive PRO14 titles after breaking free of Ulster's resistence in the second half to record a 27-5 final win at the Aviva Stadium.
Robbie Henshaw's 45th-minute intercept try and a closing score from Caelan Doris were the highlights as Leo Cullen's outfit, who remain unbeaten in all competitions this season, claimed their fifth PRO14 title in eight years.
With a Champions Cup quarter-final against Saracens just a week away, captain Jonathan Sexton was benched up to the hour mark as Ross Byrne kicked Leinster into a 10-5 half-time lead after James Lowe cancelled out James Hume's early try.
Cullen's men extended their winning streak to 25 matches ahead of the visit of Sarries - the last team to defeat them 16 months ago.
Buoyed by their late heroics against Edinburgh in last weekend's semi-final, Ulster enjoyed a dream start to their first final appearance since 2013.
Alan O'Connor's pull-back pass released Hume from 40 metres out and the young centre got away from Ronan Kelleher and Lowe to brilliantly score near the left corner.
Leinster quickly replied as Jamison Gibson-Park's cut-out pass put Lowe over out wide, the conversion neatly supplied by Byrne for a 7-5 lead before he added a penalty.
Another Byrne penalty extended the advantage and the killer blow arrived just moments later.
Henshaw gobbled up a Burns pass just inside the Ulster half and stayed clear of the chasing Michael Lowry to go in under the posts.
With Byrne's conversion making it 20-5, it was a long way back for the Ulstermen who travel to Toulouse next week in Europe's quarter-finals.
The clinching try arrived nine minutes from time when flanker Doris drove past two former Leinster players Jordi Murphy and Ian Madigan, and under the posts, with Sexton converting.