Mark Warburton’s position as QPR manager was thrown into further doubt as his side were beaten again.
A first half own goal from Jimmy Dunne followed by Cameron Archer’s strike shortly after the restart saw QPR suffer a fifth consecutive defeat.
Andre Gray pulled a goal back with a late penalty after Sam Field was fouled by Daniel Johnson.
QPR’s bad luck continued before kick-off when goalkeeper Keiren Westwood had to withdraw from the team due to illness meaning youngster Murphy Mahoney, 20, made his senior debut.
The first big chance of the afternoon fell to Andre Dozzell, who drove forward from midfield and saw a fortunate ricochet send him through on goal but his effort was well stopped by Daniel Iversen.
Iversen was called into action again to deny Ilias Chair effort from a tight angle but Preston threatened moments later when Alan Browne burst through from Archer’s flick, forcing Moses Odubajo to make a fantastic block in front of the goal-line.
But the home side had the lead before half-time when Andrew Hughes was given space out on the left to whip in a dangerous low cross for Emil Riis, with Dunne adjudged to have had the last touch.
Preston doubled their advantage shortly after half-time when Archer was allowed to cut in from the right before rifling a strike into the roof of the net past Mahoney.
Subtitute Gray went through on goal on 74 minutes but was denied by another good stop from Iversen, while Archer saw his effort from a couple of yards out blocked on the line.
Mahoney, who impressed on his debut with a string of excellent stops, made a fine save to deny Alan Browne a third.
QPR: Mahoney, Dunne, Field, Sanderson, Odubajo, Dozzell, Johansen, Amos (Thomas 56), McCallum, Chair (Gray 68), Dykes (Austin 68).
Subs not used: Adomah, Kakay, Ball.