The Lilywhites struck first when Emil Riis tapped in a deflected cross from Greg Cunningham for his 14th goal of the season.
Cameron Archer then wrapped up all three points for the visitors as he came off the bench to bag his first goal for Preston since arriving on loan from Aston Villa.
Story of the match
Riis was again involved just after the half-hour mark as he was played in by Alan Browne, but he failed to hit the target.
Four minutes from halftime, the Lilywhites opened the scoring. Whiteman's clever touch found Greg Cunningham, his cross into the area deflected goalwards and Riis bundled it over the line.
It could have been two for Preston as Ched Evans squared for Riis, but he flashed his effort well wide.
The lead was doubled as Archer came on for Riis and ten minutes later, the debutant headed home after Cunningham's shot was saved.
Man of the match: Alan Browne
The Preston skipper was brilliant. He was lively and energetic throughout the game and his quality in possession was a constant.
His creativity in setting up Riis several times shone through and he was instrumental in setting up both goals.