Carlton Morris marked his first game as Derby captain by scoring the only goal to make it two wins in four days at Pride Park for the Rams.
Morris was handed the captain’s armband by boss John Eustace because skipper Lewis Travers and No 2 Ebou Adams were unavailable and the striker celebrated in style.
Morris scored from close range to take his tally for Derby to five since his summer move from Luton.
The Rams could have had more, hitting the woodwork twice, and QPR were disappointing after their fine recent form that had seen them lose just once in eight games.
They rallied late and Ilias Chair was denied in stoppage time, but their second defeat in three games cost them a chance to get into the top seven.
Derby are making up for their poor home form and they had gone eight games at Pride Park without winning prior to beating Norwich in midweek.
Eustace now has presided over two wins and two clean sheets to make the home fans happy as they climbed five points clear of the bottom three.
Morris struck after just 10 minutes when Max Johnston clipped the ball to the back post and he finished off Sondre Langas’ effort from just a yard out.
It was all Derby and Morris and Ben Brereton Diaz went close, in between an effort from Patrick Agyemang, which was saved by QPR goalkeeper Paul Nardi.
The Rams threatened to extend their lead and Johnston was unlucky to see a free-kick hit the bar before Brereton Diaz headed against the post.
Richard Kone should have done better when he headed wastefully wide for Rangers before Karamoko Dembele saw a shot blocked and Jonathan Varane headed over.
Derby goalkeeper Jacob Widell Zetterstrom kept out Chair’s shot in stoppage time in QPR’s only shot on target.