Leinster secured a home quarter-final against Scottish side Glasgow next weekend after a stunning hat-trick from Andrew Conway guaranteed that there would be no late drama as the race for the play-offs ended in a gentle gambol.
With the cult hero Isa Nacewa leaving at the end of this month and Luke Fitzgerald once more shadowed by injury, Conway's late flourish in this semi-final could be harbinger of great things to come next season.
Conway's three tries were the highlight of an entertaining game marked by some ferocious work from Sean O'Brien as Leinster now keenly anticipate a trophy rush in the next three weeks.
On this evidence, Glasgow will be no match for the hungry Irish.
With a brisk breeze stirring up the flags on the stroke of Nigel Owens' opening whistle, both sides engaged each other with enigmatic endeavour, Leinster all inside pop passes from Leo Cullen while Ospreys chipped and grubbered at will.
Yet there was physical menace, too, Lions back-row contenders Sean O'Brien and Justin Tipuric feeling each other's hot collars after a choke tackle turnover stymied an early Ospreys incision.
Another chip and chase then pinned Shane Jennings in such a sufficiently tight corner that he was deemed to have illegally retained possession to hand an early strike to Dan Biggar – curiously the only member of the Welsh side that started the Six Nations decider not to be selected for the Lions.
Maintaining his ill luck, the out-half, who secured successive last-gasp winners here last term, was awry with his attempt and Leinster survived the early scare.
Within a couple of minutes, they were 7-0 up. A sweet passing move, the kind instigated by Joe Schmidt from the first day of his arrival, swept Leinster from left to right, before Fergus McFadden put boot to ball in order to evade the familiarly rushing defence.
As Ross Jones, the one-time Castleknock boy, stooped to gather the tricky, bouncing ball, the winger flapped at it as if trying to track down a Tayto bag flurrying violently in the wind; the ball ducked beneath his legs, Conway sneaked behind his back and the try was dotted.
Jonathan Sexton added the extras and Leinster were off and running. Thomas Habberfield caught the Jones bug, also letting the pill slip between his legs like an errant puppy.
Leinster sensed the mood and pounced. After coughing up one glorious attacking opportunity with a five-yard scrum, the lively Conway's chip returned the home side to the red zone almost immediately.
From 10 yards out on their right, Cullen briskly creamed the ball off the top of Sean Cronin's accurate delivery, the zippy Luke McGrath, hungrily grabbing the chance in more ways than one after Isaac Boss' late cry-off, evaded some slip-shod tackling before a delightful off-load allowed Conway to gleefully nab his second score. With 25 minutes gone, Leinster were bounding towards a home semi-final. At least, it seemed like that.
Ospreys, to their credit, always kept playing. And their persistence paid off eventually when Biggar's fate improved and he barged over from a quick and tap-and-go near the left-hand corner as Leinster fell into a second-quarter snooze.
Then, Alan Wyn Jones found a gaping hole in Leinster's creaking defence; sadly for him, it was created unwittingly by his refereeing compatriot who had sidled into his path.
But Jones had the last laugh, his lineout steal from more territorial pressure ultimately creating the platform for his side's second try, Ben John finishing a short side passing move that and winding Sexton in the process.
Some of Leinster's tackling was poor in this period; with the contribution of Quinn Roux hardly indicative of a star in the making. Leinster's nerves were frayed and Ospreys' tails were up.
At least Leinster had the final word, Sexton booming a long-range three-pointer to put his side 17-12 ahead and leaven the rage of Schmidt, a man well capable of breaking a few proverbial tea cups, even of the plastic variety.
Suitably fired up, Leinster doubled their advantage once more within 90 seconds, Conway securing his hat-trick after his deft chip and chase saw him easily out-run the hapless Jones, who despite being afforded a second chance to snaffle the scorer failed dismally to do so.
Sexton's conversion hit the left-hand upright and went over and, with the scrum re-emerging as a dominant force and seemingly content to allow the Ospreys possession with little penetration, you could feel the away side's hearts sink when O'Brien effected a brilliant turnover as the visitors threatened.
Sexton's superb penalty in the 55th minute pushed the advantage to 27-12, and, although Tom Isaacs rebutted, Cian Healy darted over late on and all the while Sexton – now 14 from 14 from the tee since his return in Zebre – kicked like a dream.
LEINSTER – R Kearney; A Conway, F McFadden, I Madigan, I Nacewa; J Sexton, L McGrath (J Cooney 62); J McGrath (C Healy 62), S Cronin (R Strauss 62), J Hagan (M Bent 68); L Cullen (capt, D Toner 68), Q Roux; R Ruddock, S Jennings (J Murphy 60), S O'Brien (A Goodman 78)
OSPREYS – R Fussell (M Morgan 70); T Habberfield, A Beck, B John, R Jones (T Isaacs 57); D Biggar, R Webb (J Spratt 16); D Jones (D Arhip 60), S Baldwin, A Jones (R Bevington 47); AW Jones (capt), J King; J Tipuric, S Lewis, J Bearman (A Morgan 69).
Ref – N Owens (Wales)