Two late Isa Nacewa penalties saw Leinster beat Racing 92 15-12 to claim a record-equalling fourth European title at the San Mames stadium in Bilbao on Saturday.
The Irish province, who matched Toulouse's four continental triumphs having previously won in 2009, 2011 and 2012, completed their European campaign unbeaten in nine games.
It also meant that Leo Cullen, who won the European Cup three times as a Leinster player, became the first person to lift the trophy both as player and as coach.
Racing were dealt a blow just before kick-off when All Blacks legend Dan Carter withdrew from the bench with injury. South African Pat Lambie started at No.10 but didn't last three minutes before injuring his knee, Remi Tales taking over.
A high Garry Ringrose tackle following Lambie's injury saw Teddy Iribaren, deputising for the injured Maxime Machenaud at scrumhalf, open the scoring with a penalty in a tight game where defence was the winner and wide, expansive attack never an option.
Leinster, boasting a host of players who helped Ireland to the Six Nations Grand Slam this season, came out of their shell on the quarter-hour mark, Johnny Sexton marshalling the midfield in waves of attacks.
The Irish province's veteran New Zealand-born captain Nacewa, who retires at the end of the season, broke the line, but the wing capped once by Fiji was hauled back by opposite number Teddy Thomas.
An infringement by the Parisians saw Sexton knock over a simple penalty to draw the scores level, but Iribaren restored the lead with his second three-pointer.
Using flank Dan Leavy as the main hitman for flat ball as Leinster played percentages around the gainline, the Irish started to make inroads.
But Racing's heroic defence in the face of Leinster's increasing dominance of possession held firm and when Sexton opted to run a kickable penalty, Camille Chat was in place to pluck the ball from Leavy's arms at a ruck to win a penalty and the Parisians cleared their lines.
Racing's giant Fijian lock Leone Nakarawa was lucky not to be given a yellow card after a deliberate knock-on with Leinster again on the front foot.
This time, Sexton made no mistake and booted his second penalty to again equalise the scores at 6-6 going into half-time.
Iribaren nailed his third penalty five minutes into the second period as Racing tested the Irish defence.
Sexton badly fluffed a long-range effort as Leinster, for all their territorial dominance, couldn't quite find their rhythm amid Racing's desperate, hard-hitting defence.
The Ireland flyhalf was more successful with his fourth kick, pulling the sides level, with signs of fatigue heralding a raft of replacements.
Tales and Racing's South African-born France flank Bernard Le Roux were then penalised at a ruck, but Sexton went wide with a monster 48-metre penalty, mirrored shortly after by Iribaren.
With 10 minutes to play, Leinster brought down a maul and it was the unheralded Iribaren, who previously played for Montpellier and Brive, who booted Racing into the lead with his fourth penalty.
Leinster responded immediately, Australian flank Scott Fardy exploding down the wing.
Offside in midfield and Nacewa stepped up to, once again, draw his Irish side level.
Another offside in front of their posts and Racing were made to pay, Nacewa kicking his second penalty to hand Leinster a 15-12 lead.
Tales then went wide with an injury-time drop-goal that would have seen added time.
Pens: Sexton 3, Nacewa 2
For Racing 92:
Pens: Iribaren 4
Leinster: 15 Rob Kearney, 14 Jordan Larmour, 13 Garry Ringrose, 12 Robbie Henshaw, 11 Isa Nacewa (captain), 10 Johnny Sexton, 9 Luke McGrath, 8 Jordi Murphy, 7 Dan Leavy, 6 Scott Fardy, 5 James Ryan, 4 Devin Toner, 3 Tadhg Furlong, 2 Seán Cronin, 1 Cian Healy.
Replacements: 16 James Tracy, 17 Jack McGrath, 18 Andrew Porter, 19 Rhys Ruddock, 20 Jack Conan, 21 Jamison Gibson-Park, 22 Joey Carbery, 23 Rory O’Loughlin.
Racing 92: 15 Louis Dupichot, 14 Teddy Thomas, 13 Virimi Vakatawa, 12 Henry Chavancy, 11 Marc Andreu, 10 Patrick Lambie, 9 Teddy Iribaren, 8 Yannick Nyanga, 7 Bernard Le Roux, 6 Wenceslas Lauret, 5 Leone Nakarawa, 4 Donnacha Ryan, 3 Cedate Gomes Sa, 2 Camille Chat, 1 Eddy Ben Arous.
Replacements: 16 Ole Avei, 17 Vasil Kakovin, 18 Census Johnston, 19 Boris Palu, 20 Baptiste Chouzenoux, 21 Antoine Gibert, 22 Remi Tales, 23 Joe Rokocoko.
Referee: Wayne Barnes (England)
Assistant referees: JP Doyle (England), Tom Foley (England)
TMO: Rowan Kitt (England)