Leinster will head to Twickenham or Bordeaux on April 29, depending on the winners of Sunday's Vicarage Road tie, after crushing an outclassed Blues outfit.
Gavin Henson's high-profile dismissal from the Blues and his fellow Wales international centre Jamie Roberts undergoing knee surgery this week overshadowed their trip to Dublin.
And Leinster showed no mercy, ripping their opponents apart as Isa Nacewa, Rob Kearney and Brian O'Driscoll scored first-half tries to end the contest after 40 minutes.
Full-back Kearney added his second touchdown within seven minutes of the restart, and although the Blues displayed touches of attacking intent, they were restricted to a Leigh Halfpenny penalty for their only points.
Fly-half Jonathan Sexton kicked 14 points for the home side via four conversions and two penalties as they booked a fourth successive Heineken semi-final appearance.
The second period was a damp squib, yet it hardly mattered from the home side's perspective as a 24-point interval advantage meant Leinster's sights were on the semi-finals from an early stage.
O'Driscoll, fully recovered from the shoulder injury that sidelined him for this season's entire RBS 6 Nations Championship, made his first Heineken Cup start since the Millennium Stadium final against Northampton last May.
World Cup-winning New Zealand lock Brad Thorn also featured for Leinster, while the Blues replaced the injured Roberts in midfield with Dafydd Hewitt as they looked to put a difficult week behind them that began with their celebrity centre Henson being sacked.
Halfpenny and Sexton exchanged early penalties, a bloodied Halfpenny dusting himself down to find his range from just inside Leinster's half, but the home side soon began to look more menacing in attack.
And that sense of adventure was rewarded after 14 minutes when Sexton sliced through the Blues defence, finding Kearney in support, and Nacewa crossed on the overlap.
It was a simple, but brilliantly-worked try by the home side, and Sexton's conversion made it 10-3, leaving the Blues with plenty to ponder.
There were no immediate signs of an improvement from the visitors' perspective, with a second Sexton penalty increasing Leinster's advantage to 10 points and keeping Cardiff at a safe distance.
The Blues offered little in attack, and what possession they did manage to move wide, Leinster comfortably dealt with it.
There was worse to come for the Blues when scrum-half Eoin Reddan shredded their defence from 40 metres out, a break that ended with Kearney sprinting over unopposed.
Sexton added the extras but Leinster were in no mood to switch off and they added a third try before the break when an exquisite inside ball from Sexton found wing Luke Fitzgerald, and he sent the supporting O'Driscoll over.
Sexton again converted, making it 27-3 - and a case of game over - before referee Dave Pearson's half-time whistle had even sounded, leaving the Blues facing a prolonged damage-limitation exercise.
But there were no signs of an improvement after the break as slick Leinster passing, sparked by workaholic prop Cian Healy, produced another Kearney touchdown.
Sexton's conversion attempt dipped over via an upright, and Cardiff's faces almost matched their pink shirts in terms of the degree they had been embarrassed in their biggest game of the season.
The Blues enjoyed territorial supremacy in the second half, but even a consolation try eluded them when flanker Martyn Williams narrowly failed to ground possession.
Referee Pearson required a second opinion from television match official Geoff Warren, who rightly ruled it was not a try, and Leinster then effortlessly moved upfield.
A crowd of just over 50,000 were eager to see a final flourish from their heroes, but the game had lost a lot of its tempo as both coaches utilised their replacements' benches.
For a European quarter-final it was horribly flat, and the Blues ended a debilitating occasion for them in suitably low-key fashion when wing Tom James was sin-binned.
Leinster laid siege in search of a fifth and final try, but although it did not arrive, they had accomplished their task in convincing fashion.