Scot Gemmill's first goal for Preston ended a slump for the home team but put Bradford a step nearer relegation.
Alan Combe tipped Graham Alexander's shot over the crossbar and Simon Lynch volleyed wide in a poor first half.
Gemmill latched onto Dickson Etuhu's pass and slipped the ball past Combe with the first attack after the break.
Michael Branch volleyed over as Bradford searched for an equaliser while Jonathan Gould saved from Nicky Summerbee as Preston held out.
North End went into the game without suspended strike duo Ricardo Fuller and David Healy, who have
scored a combined total of 31 times this season
But Preston managed to win for the first time in seven games - ending their worst stretch of form for six years.
Bradford's battle to beat the drop is looking increasingly
Bryan Robson's team are second from bottom of the Division One table - 11 points adrift of safety.
Preston: Gould, Alexander, Lucketti, Davis, Michael Jackson,
Broomes, McKenna, Gemmill, Etuhu, Lynch, Cresswell. Subs:
Lonergan, Koumantarakis, Edwards, Briscoe, Keane.
Bradford: Combe, Atherton, Bower, Wetherall, Edds, Cadamarteri,
Heckingbottom, Emanuel, Summerbee, Windass, Branch. Subs:
Paston, Kearney, Wolleaston, Muirhead, Forrest.
Referee: G Cain (Merseyside).