Matthew Rose was the unlikely hero for QPR as his solo strike extended his side's unbeaten run to seven deadly wins.
In a tense London derby at Loftus Road, Rose came up trumps in the 22nd minute to push QPR five points clear of their London rivals at the top of the Championship.
QPR came close to breaking the deadlock after just four minutes when Mark Bircham's 25-yard shot fell straight into the path of West Ham keeper Stephen Bywater.
West Ham forced their way back into the game and Marlon Harewood was unfortunate to see his left-foot shot fall just past the post on 11 minutes after he cleverly weaved his way into the penalty box.
Harewood caused problems again for the QPR defence just three minutes later when he broke free into the Rangers half.
The prolific forward laid a clever ball into the path of Nigel Reo-Coker, but with the goal at his mercy, the England Under-21 midfielder dragged his shot wide of the post.
And West Ham were made to pay for that missed opportunity when QPR opened the scoring after 22 minutes.
Lee Cook's clever pass released Rose into the box and the QPR defender coolly slotted the ball past Bywater into the corner of the net.
West Ham refused to lie down and almost got back on level terms on 29 minutes when Steve Lomas drive from the edge of the box produced a fine save from Chris Day diving low down to his left.
Paul Furlong could have added a second for the home side on the stroke of half-time when his deflected header fell inches wide of the goal.
Harewood almost grabbed an equaliser on 63 minutes when his fiercely taken free-kick produced another good save from Day.
QPR should have sealed all three points on 77 minutes when Furlong's cross eluded his fellow team-mates inside the box.
The ball eventually fell to Martin Rowlands who fired a half-volley over the crossbar.