Most of the damage was done in a dominant first-half display from the hosts, with Robbie Henshaw’s late breakaway score making it 22-3 and adding to earlier tries from Isa Nacewa and Jack Conan.
Joey Carbery’s attacking instincts from full-back earned him the man-of-the-match award, but former Leinster favourite Jimmy Gopperth sparked a revival from the visitors, converting Christian Wade’s try and his own effort on the hour mark.
However, Leinster seized control again in the final quarter and replacement McFadden’s seven-pointer sealed his side’s trip to France in three weeks’ time against either Clermont Auvergne or Toulon, who play today.
Apart from Wasps’ purple patch in the third quarter, they were second best on the day.
Leinster were the early aggressors in this meeting of the current PRO12 and Premiership leaders, and six minutes had elapsed when a 33-metre penalty from Jonathan Sexton punished Joe Launchbury’s side-entry.
After Wasps blew their first two lineout opportunities, with Nathan Hughes being turned over and the heavily targeted Danny Cipriani passing straight into touch, they survived a Garry Ringrose-led break up the right wing.
However, strong runs from Adam Byrne and Dan Leavy got Leinster straight back into scoring range and Carbery’s skip pass released captain Nacewa for an unconverted 14th-minute try in the left corner.
Leinster errors saw them cough up a penalty from an attempted maul and then prop Tadhg Furlong, who was a busy figure in open play, was pinged for a tackle off the ball which Gopperth turned into three points.
However, the counter-attacking Carbery soon knifed through along with McFadden following a loose Wasps kick, and their lovely interplay on the right released No.8 Conan for a cracking 33rd-minute score.
Sexton converted and also added the extras to Henshaw’s opportunist try which saw Devin Toner rip the ball free from a Wasps maul and Leavy, Sean O’Brien and Sexton combined to send the centre surging over.
Sexton split the posts with another penalty in the 48th minute, but five minutes later, Wade’s blistering pace earned Wasps their first try, the winger dotting down his own grubber kick to the right of the posts after Carbery, returning a kick, had been turned over.
Gopperth converted to reduce the arrears to 15 points and play became increasingly fractured.Then Gopperth produced a classy finish, evading two tacklers from the edge of the 22 and converting for good measure. Suddenly, Leinster were only eight points ahead.
A sidestepping run from Ringrose almost produced the ideal response from the Irish province, although Wasps forced a subsequent knock-on. In the end, Leinster’s stranglehold of territory and a heavy defensive workload saw Wasps give way seven minutes from time.
Toner barged through to a few metres out and produced quick ruck ball for McFadden to slither over under pressure. Sexton’s conversion was the final nail in the coffin.