Mame Biram Diouf (twice), Ryan Nelsen, Gael Givet and El-Hadji Diouf could all have given their side a comfortable lead.
However, the 20-year-old Hoilett showed them all how it should be done with a shot from the edge of the penalty area late in the second half.
Air heads: Rangers' Alejandro Faurlin beats Michel Salgado in the air
The sparse crowd of 10,284 - 14,238fewer than the one which witnessed the midweek Barclays Premier Leaguevictory over Liverpool - was given plenty of goalmouth action but hadto wait until 14 minutes from time for the decisive finish.
It took Rovers just 51 seconds tocarve out their first chance when Mame Biram Diouf fired across PaddyKenny but wide of the far post.
There then followed almost aprocession of chances for the home side - exactly the type which onWednesday they had buried against the Merseysiders.
At the heart of it all was Morten Gamst Pedersen, who was the major creative force from central midfield.
When he was not swinging in temptingcrosses or firing in free-kicks he was prompting and probing in anattempt to find the one pass which would break down QPR's defence.
Hoilett, man of the match againstLiverpool, also put in another positive display and eventually providedthe killer blow which had been so lacking in everything previously.
Rovers should have been well out ofsight by that point, however, as they had enough opportunities in thefirst half alone to put the result beyond doubt.
Nelsen headed wide Pedersen's inswinging free-kick before only the brilliance of Kenny kept the score goalless at half-time.
Pedersen's 18th-minute cross fromthe right brilliantly picked out Mame Biram Diouf but the Senegalesestriker saw his header expertly tipped over.
Seconds later the goalkeeper produced an identical save to deny Givet, who had deflected Pedersen's cross goalwards.
It was the Frenchman's lastcontribution as he soon departed on a stretcher after a collision withJamie Mackie which also saw the QPR forward carried off after lengthytreatment.
Injury blow: Rangers' Jamie Mackie is carried off
When the action resumed Pedersen wasquickly back into his stride, teeing up El-Hadji Diouf on the edge ofthe penalty area only for him to sidefoot over.
QPR had limited opportunities of their own but although they were infrequent they were decent chances.
Before he was injured Mackie's shotbeat Mark Bunn only for Nelsen to clear off the line while PetterVaagan Moen's fizzing 40-yard free-kick in first-half added time wastipped onto the crossbar by Bunn.
Mame Biram Diouf should have put hisside ahead on the hour after getting around the back of the QPR defenceto latch on to Pedersen's free-kick.
However, his attempt at controllingthe ball on his thigh was poor and it shot away from him and off thepitch close to the post.
Hoilett was closer as his shot, after a weaving run along the edge of the penalty area was deflected just over by Clint Hill.
El-Hadji Diouf then drove into theside-netting as Rovers began to turn up the pressure, which ultimatelyresulted in Hoilett's winner.
The breakthrough finally came in the76th minute when El-Hadji Diouf cut in from the left, beat a couple ofdefenders and squared the ball to Hoilett on the edge of the penaltyarea.
The 20-year-old's perfectly-aimed shot beat Kenny's dive and nestled in the corner of the net.
Jason Roberts, who came on as asubstitute at half-time, should have made the result safe moments laterbut headed wide unmarked from Josh Morris' cross to the near post.
With six minutes to go KasparsGorkss' header hit the crossbar - the second time the visitors had beendenied by the woodwork - and it was obvious their luck was not in.
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