Last season's Heineken Cup champions Toulouse were dethroned by Leinster in a bruising semi-final showdown at the Aviva Stadium.
Brian O'Driscoll's 59th-minute try and Jonathan Sexton's 22-point kicking haul proved crucial as Leinster avenged last May's semi-final loss to the same opposition.
Joe Schmidt's side twice came from behind to show their class in an absorbing second half, using their physicality up front to knock Toulouse off their stride and progress to their second Heineken Cup final in three years.
Florian Fritz profited from a wicked bounce of the ball to score Toulouse's fifth-minute opener, with Leinster using their forward power to set up a 31st-minute reply from man-of-the-match Jamie Heaslip.
The hosts nipped into a 16-13 half-time lead courtesy of Sexton's injury-time penalty, but Louis Picamoles sauntered over for Toulouse's second try.
Leinster used their bench intelligently and Sexton's place-kicking was assured, moving them back ahead until O'Driscoll struck and, although replacement Nicolas Bezy kicked Toulouse to within six points, Sexton had the final say.
Yannick Nyanga, part of a formidable Toulouse lineout, stole Richardt Strauss' first throw and Leinster's eager scrum coughed up a free-kick for an early engagement.
O'Driscoll infringed at the breakdown, allowing David Skrela his first shot at the posts from the left. The out-half's kick bounced down off the left-hand upright and away from the covering Leinster players for the onrushing Fritz to gather and score.
Skrela's conversion was cancelled out by a close-in penalty from Sexton, following some fleet-footed attacking from Gordon D'Arcy and O'Driscoll.
The battle between the number 10s intensified as Skrela lofted a drop goal over and Sexton popped over his second penalty, rewarding some solid breakdown work from Cian Healy and Sean O'Brien.
Cedric Heymans showed some nice touches when entering the attacking line and D'Arcy threatened again in midfield, but the sides cancelled each other out as the first half wore on.
Space was at a premium until Leinster lifted the tempo coming up to the half-hour, pummelling away at Toulouse's defence and finding holes close to the posts. The weight of pressure told when Heaslip's outstretched arm reached the line, amid a pile of bodies.
Confirmation of the try came from television match official Graham Hughes, with Sexton's conversion making it 13-10. Toulouse raised their game immediately, Clement Poitrenaud and Heymans finding a gap near the halfway line.
The French giants kept on the front foot and after referee Dave Pearson sin-binned O'Driscoll for coming in on the wrong side a few metres out from the home line, Skrela levelled the scores.
Argentinian lock Patricio Albacete then coughed up a needless late penalty, allowing Sexton to kick Leinster ahead going into the break.
Toulouse were quick out of the blocks in the second half, determined to use their numerical advantage. Heymans put a brilliant grubber kick through for Vincent Clerc, who was unable to control the bobbling ball with the try-line at his mercy.
Leinster conceded a five-metre scrum, however, and a powerful set-piece from Toulouse saw the sharp Jean-Marc Doussain draw in Eoin Reddan's tackle and pass for Picamoles to score.
Replays showed Nyanga holding O'Brien back off the ball, but the score stood and Skrela tagged on the extras. Back came Leinster, Sexton splitting the posts five minutes later.
The game was really opening up, Heymans sparking a trademark counter-attack full of flair and a bloodied Healy putting in a barnstorming run in response.
Healy's replacement Heinke van der Merwe forced Census Johnston to pop up in a scrum and Sexton's trusty right boot made it 22-20.
That scrum seemed to enliven Leinster's play and they found an extra gear as Strauss, O'Brien and Nathan Hines barged their way forward.
From another explosive phase from the forwards, Sexton gathered a loose ball and took contact before replacement Isaac Boss passed for O'Driscoll to slip by Clerc and Johnston for his try.
Sexton's conversion put nine points between the sides at 29-20 and Toulouse's title was suddenly slipping from their grasp. Willed on by their red and black-clad supporters in a 50,073-strong crowd, Toulouse were not going down without a fight.
They worked a one-on-one out wide, where Gregory Lamboley was floored by Isa Nacewa's textbook tackle and Heaslip secured the turnover at the ruck.
In a strength-sapping climax, Leinster held their nerve to justify their pre-match favourites tag. Bezy's penalty from just inside the Leinster half increased the tension, but Sexton knocked over his eighth successful kick of the day for a sweet finish.