Harry Redknapp's men started the day 11 points adrift of leaders Leicester City, but were on the back foot as early as the 10th minute as Danny Williams gave Reading the lead at Loftus Road.
Kevin Doyle then tapped home from close range to equalise against his former club as the sides went in all square at the break.
Alex Pearce restored the Reading lead shortly before the hour mark with another header and the advantage was doubled moments later when Garath McCleary thumped home a 25-yard effort.
Former QPR defender Kaspars Gorkss was given his marching orders for a reckless challenge on Junior Hoilett in the 71st minute, but the hosts were unable to make the extra man count.
Joey Barton came closest to reducing the deficit, sending a left-footed volley fizzing over the crossbar four minutes from the end.
The result strengthens Reading's position in the play-offs and pulls them to within four points of fifth-placed Nottingham Forest.
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