The defending champions held sway for the majority of the contest with Ulster unable to build on a lively start as first-half tries from Sean O'Brien and Cian Healy gave Leinster a lead they never really looked like surrendering.
A penalty-try early in the second period gave Leinster real breathing space and, while Ulster never threw in the towel, Jonathan Sexton's immaculate kicking ensured they were unable to get back within striking distance.
Leinster then finished with a flourish as late tries from replacements Heinke Van der Merwe and Sean Cronin ensured they recorded the biggest-ever win in a Heineken Cup final.
Ulster began on the front foot with centres Darren Cave and Paddy Wallace both making strong breaks and that early momentum led to a seventh minute penalty - Leinster killing the ball at the breakdown - which Pienaar coolly stroked over.
But Ulster quickly found themselves under pressure from the restart as Leinster came round from their sluggish start and the men in white paid the price for spurning a couple of opportunities to clear their lines.
Having turned the ball over following a scrum in the Ulster 22, Leinster went through several phases of possession and, after Rob Kearney had gone close, there was a sense of inevitably when flanker (Sean) O'Brien reached out to touch down from close range - although the try was only given after consultation with the video official. Sexton slotted a solid conversion on the angle.
Leinster had the chance to extend the lead on the quarter-hour mark after Ulster's Chris Henry was penalised in midfield, but this time Sexton dragged his kick wide of the uprights.
Despite that, Leinster were steadily assuming the upper hand, Brian O'Driscoll threatening with a couple of breaks. And it was the Leinster skipper at the heart of the move when the holders extended their lead on the half-hour mark.
Having cut back inside, O'Driscoll produced a wonderful flicked backhand offload to O'Brien who burst clear towards the Ulster try-line. Although he was hauled down just short, Leinster had numbers in support and when the ball was spun wide Cian Healy was on hand to bulldoze past Andrew Trimble and roll over for a try which Sexton converted.
Ulster responded and earned good position in the Leinster 22 on their next attack, but they were unable to come away with any points as Paddy Jackson snatched at his drop-goal attempt, dragging it wide of the posts.
They were, though, given a timely and much-needed boost on the stroke of half-time as Pienaar booted a spectacular penalty from inside his own half to make the interval scoreline.
But any hopes they held of battling their way back into the contest suffered a hammer blow just five minutes into the second period as Leinster were awarded a penalty try. It came about after confusion between Stephen Ferris and Jackson had seen the fly-half kick for touch after the ball had been carried back in to the Ulster 22.
Having won the subsequent line-out, Leinster built up a head of steam through a rolling maul and when they were brought down just short of the line referee Nigel Owens deemed it had been done illegally and ran to the sticks with his arm raised - Sexton added the simple conversion.
Pienaar kicked his third penalty after Leinster had been caught offside and O'Brien warned for a high tackle, but Sexton responded in kind moments later to ensure the men in blue re-opened the 15-point margin.
Ulster breathed new life into the contest on the hour mark. Having made their intentions clear by turning down an easy penalty in front of the posts in favour of a scrum, they got what they wanted a couple of minutes later as second-rower Dan Tuohy rumbled over out wide after a fine burst and overhead pass from Wallace.
But Pienaar missed the conversion and when Rory Pest was pinged for playing the ball whilst off his feet as Leinster attacked in the 67th minute, Sexton again bisected the posts with a penalty to make the score 27-14.
The fly-half killed the contest with his third penalty six minutes from time after Stefan Terblanche was sin-binned for a tip-tackle on replacement Sean Cronin - his kick taking the champions two converted scores clear.
A man down, a deflated and exhausted Ulster were ruthlessly exposed in the closing stages as replacements Heinke Van der Merwe and Cronin both romped in for easy tries to ensure Leinster recorded a record winning margin on a day of real triumph for the Irish outfit.
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