Ferdinand – released by Manchester United in the summer – was out-muscled by James Chester at the far post, allowing the Tigers defender to head in Stephen Quinn’s 52nd minute corner for what proved the winner.
But Hull had keeper Allan McGregor to thank for preserving the three points with the keeper saving Charlie Austin’s late penalty after Chester was harshly penalised for hand ball.
Ferdinand had a chance himself to grab the equaliser moments before the spot-kick but his tame effort was hacked off the line by Tom Huddlestone.
Harry Redknapp's side enjoyed the majority of possession during the contest but Rangers were ultimately made to pay the price for a lack of cutting edge in the final third.
Instead, it was Chester who made the decisive contribution as he earned the Tigers their first win at Loftus Road since 1963.
Loic Remy, who could have been wearing the red of Liverpool had he not failed a medical earlier this summer, was certainly the home side's greatest threat but Hull's well-organised defence did just enough to keep the Frenchman at bay.
City enjoyed the better of the opening period, but the hosts established a foothold and were almost gifted a breakthrough when McGregor failed to shepherd the ball out of play for a goal-kick and Austin stole possession out wide.
The striker could have tried a long-range shot into the open net but instead he teed up Jordon Mutch at the back post, who missed the ball completely on his weaker right foot.
Remy, who was lacklustre early on, grew into the game and started causing Hull's back three problems with his direct running in behind.
Just before the half-hour mark, the striker earned a free-kick on the edge of the area which Joey Barton clipped into the side-netting, and moments later he again broke free to find Mutch, who headed narrowly wide.
QPR continued to look the more likely scorers and almost broke the deadlock before half-time as Steven Caulker rose highest to a corner, but his header was cleared off the line by Andrew Robertson.
The home side started the second half brightly but it was Hull who grabbed the opener in the 52nd minute when Chester out-muscled Ferdinand and headed home.
Rangers responded positively to going behind but, for all their possession and forward-running, were unable to carve out a decisive chance.
Instead, it was the visitors who should have doubled their lead when Tom Ince was put through on the counter-attack, but the 22-year-old's tame finish was blocked by the legs of Rob Green.
Redknapp threw on Junior Hoilett, Bobby Zamora and Matt Phillips in the latter stages in search of an equaliser, and it was Hoilett who earned his side a spot-kick when his cross was adjudged to have struck the hand of Chester six minutes from time.
Austin stepped up and fired low to McGregor's right but the Hull keeper read the shot and palmed the ball away.
Zamora and Remy both had chances to equalise in the dying moments but the former took too long and the latter was denied by McGregor as Hull held on for all three points.