Striker Rob Hulse, who nearly missed the match through illness, calmly tapped home the winner just before half time after QPR had been the livelier side early on.
But Leeds had to play the last 25 minutes with ten men after foolish David Healy, Northern Ireland's hero in their shock win over England earlier this month, was sent-off for a needless kick on Marc Bircham. QPR had neither the ideas not the guile to break-down the visitor's rearguard after that.
The result sees United leapfrog Rangers in the Championship table and means QPR have only won one of their last seven matches after a promising start to the season.
Despite a virus that threatened to rule a number of Leeds players out of the clash, Kevin Blackwell's team only made one change from the side that lost to Sheffield Wednesday on Tuesday, Hulse coming in for Richard Cresswell.
The Londoners, without the banned Tommy Doherty and injured captain Kevin Gallen, were looking for their first win over Leeds almost ten years to the day they secured a 3-1 win at Elland Road in the Premiership, but it wasn't to be their day.
Yet in a lively start on a sunny afternoon in west London, it was Rangers who came out of the traps the sharpest.
After just two minutes an uncertain Neil Sullivan dallied on a clearance allowing ex-Chelsea striker Paul Furlong to charge the Scotland international goalkeeper down, but the Leeds fans behind Sullivan's goal were spared a disastrous start as the ball ran to safety.
Two minutes later, winger Gareth Ainsworth went on a mazy dribble into the penalty box but he was eventually crowded out before he could get a shot in.
But it was the visitors that should have taken an early lead as they nearly hit QPR with a sucker punch in their first attack. Eddie Lewis crossed for Hulse who dummied, leaving Jonathan Douglas with what seemed like a simple finish from six yards.
But the midfielder skied his effort into the top tier of the Loft instead of registering his second of the season.
With both sides failing to keep control of the ball in midfield, it made for an entertaining opening period, even if chances were being created out from mistakes rather than incisive passing.
And the uncertainty spread to Leeds' backline with the experienced Sean Gregan nearly caught out on two occasions trying to shepherd the ball back to Sullivan.
Rangers nearly took advantage of Leeds' carelessness when Dean Sturridge rose high to head down for strike partner Furlong, but he struck his left-foot volley from six yards into the ground and failed to trouble Sullivan.
Midway through the half Rangers fans were up in arms claiming a penalty when Sturridge went down under the challenge of Stephan Crainey but referee Peter Walton correctly waived play on.
But Leeds could still not shake off their careless defending. The hapless Gregan, who was having a torrid half against the pace of Sturridge and the power of Furlong, again slipped allowing Sturridge to fire in a thunderous drive that went straight down the throat of Sullivan.
The veteran defender also went into the referee's book for a late challenge on Sturridge.
After surviving a sticky period without conceding, Leeds came back at their hosts and could have gone ahead had top scorer Healy been more alert when unmarked at the back post.
But the travelling fans from Yorkshire did not have to wait much longer to celebrate as sloppy marking from Lewis' left-wing free-kick allowed Hulse all the time in the world to guide home his third goal of the season from close range six minutes before the break.
And the ex-West Brom striker, signed for £1.1million from The Hawthorns in the summer after a loan spell at Elland Road last season, could have had another moments later, but saw a header flash wide.
QPR could point to the loss of the lively Mauro Milanese who went off with a hamstring injury on 28 minutes for their loss of shape.
But whatever was said at half-time to change things around, it was Leeds who came closest in the second period after Gylfi Einarssson's header was cleared off the line from a corner.
Healy was also starting to cause more problems for the Rangers rearguard and saw an effort easily gathered by Simon Royce. But the former Preston striker was then involved in the game's most contentious moment a few minutes later.
He was shown a straight red card by referee Walton for appearing to kick out at Marc Bircham after a tangle between the pair at a throw-in. A melee then ensued as Leeds players felt Bircham had over-reacted to Healy's kick, but the challenge left the official with little option but to send Healy off.
Unsurprisingly, the ten men defended in numbers to hold on to their slim advantage. It meant the second half lacked the action and the exciting of the opening period, especially as Gregan and co had cut out many of their first-half errors.
It meant Rangers were limited to long-range efforts with Steve Lomas and Furlong both failing to trouble Sullivan.
But Ian Holloway's side did have a glorious chance to snatch a point but Georges Santos headed over from Martin Rowlands' cross when he should have buried the chance with 15 minutes left.
Man of the Match: Rob Hulse - The striker had been doubtful before the match with a virus but he proved his fitness with the winning goal and led the line well throughout.