Mikele Leigertwood got the only goal of the game to end QPR's nine-game winless run as Swansea lost to London opposition for the second successive game - after going down 3-1 at home to Crystal Palace on Saturday.
Swansea were without 21-goal striker Jason Scotland who had to settle for a place on the bench.
And they could have done with their top scorer in the opening exchanges as they were restricted to long-range efforts.
QPR gave a debut to their loan signing from Tottenham, Adel Taarabt, but it was youngster Hogan Ephraim who had the best chance early on.
His run from the halfway line seemed to be blocked off on the edge of the area by Ashley Williams, but referee Graham Horwood was unmoved.
But on the half-hour mark the scrappy contest came to life when Leigertwood gave the hosts the lead.
Jordi Lopez swung in a deep cross from a free-kick on the right wing and Leigertwood shrugged off his marker to head home past Dorus de Vries in the Swansea goal.
The Swans nearly got straight back into the game less than 30 seconds after the break when Gorka Pintado shot from four yards but was denied by a brilliant Radek Cerny save.
Cerny then made another great save to deny Thomas Butler seconds later.
Taarabt has his first chance on the hour mark when his curling shot from the edge of the area just went over the bar.
The game petered out to a uninspiring end, but that will not bother Rangers boss Paulo Sousa one bit as he got his first win since January and kept his team's remote play-off dreams alive by moving to within seven points of the top six.