He scored four minutes after half-time when he held off Mauro Milanese to guide in a left-foot finish.
Kightly could have had a hat-trick, bringing a fine save from Simon Royce and missing when clean through.
QPR had fleeting chances but Wolves dominated after the break and could have added to their slender lead.
QPR manager John Gregory:
"A new manager always makes an impact and it got a bit more out of everyone when I took over, which was not necessarily to do with me.
"The players have now slipped back to being what they were before I took over and they need to find that extra 20%.
"As soon as Wolves scored the players changed and they became very nervous. Our goalkeeper Simon Royce kept us in it at times."
Gregory also revealed after the game that he has extended the loan deal of Chelsea midfielder Jimmy Smith until the end of the season and also hopes to do the same with his club-mate Michael Mancienne.
Wolves manager Mick McCarthy on striker Michael Kightly:
"I told Michael he should have scored four and he should. I am hard to please and he knows that.
"He looks a good acquisition. He is on loan from Grays and I would think we would sign him permanently. He looks like he is going to score every time he gets into the box and he is taking his chance.
"I don't have a clue why we keep having a poor first half. Perhaps we should give them a rollicking before the game starts, because the second half performance was terrific."
QPR: Royce, Bignot, Rehman, Mancienne, Milanese, Rowlands, Smith, Bircham (Furlong 66), Gallen, Ray Jones, Blackstock.
Subs Not Used: Cole, Ward, Baidoo, Bailey.
Wolverhampton: Murray, Little, Breen, Craddock, McNamara, Kightly, Olofinjana, Potter, McIndoe, Bothroyd, Craig Davies (Clarke 76).
Subs Not Used: Oakes, Edwards, Johnson, Ricketts.
Booked: Breen, Bothroyd.
Goals: Kightly 49.Att: 12,323
Ref: C Foy (Merseyside).