Two tries from Rob Kearney and a score apiece from Isa Nacewa and Brian O'Driscoll subdued the Blues, whose only points came via the boot of full-back Leigh Halfpenny in the second minute.
Five sides separate Leinster and Blues in the RaboDirect PRO12 table and the European champions' first-half performance proved why as they amassed a 27-3 half-time lead with fly-half Jonathan Sexton scoring 12 points.
Sexton slotted his first penalty after eight minutes and shortly afterwards Nacewa's try set the champions on the way to a thirteenth consecutive Heineken Cup victory.
Sexton made the initial break and sped away before passing to Kearney who fed Nacewa and the former Auckland Blues flyer went over in the corner.
Kearneywent from provider to finisher when he seized on Eoin Reddan's break to cross just before the half-hour mark.
O'Driscoll rolled back the years with a cracking try after 34 minutes thanks to Luke Fitzgerald's neat angle off an inside pass from Sexton. He zoomed through the vacant Blues' defence finding his outside centre up in support.
The Blues regrouped in the second half but Kearney's second try in the 46th minute put the game beyond doubt.
Backs and forwards combined elegantly and O'Driscoll created the opportunity for Kearney to dive over with Sexton adding the extras.
Those were to be the last points of the game but the Blues had a try appeal turned down by the video referee after openside Martyn Williams crossed Leinster's line but he was adjudged to have not grounded the ball.
Two minutes from time frustration boiled over for the visitors' Tom James and he was yellow carded for tackling Isaac Boss without retreating ten metres.
The Irish province will travel to face either Saracens or Clermont Auvergne in the last four.
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