The Tigers' battle to avoid relegation was given a major boost thanks to goals by Nicky Forster on 29 minutes and then a diving header from David Livermore midway through the second half.
Hull midfielder John Welsh had to be replaced by Livermore after only five minutes when the ex-Liverpool man was stretchered off after suffering what appeared to be a serious leg injury following a hefty challenge in midfield.
The home side took the lead though when Ray Parlour swung in a right-footed corner which landed on the head of Forster at the back post and he calmly nodded the ball into the net from close range.
Preston came close to equalising moments later as Chris Sedgwick swung in a right-footed effort from just outside the box, but the shot sailed over the crossbar.
David Nugent had to be replaced by Patrick Agyemang in the 32nd minute after suffering a leg injury following an aerial challenge with Hull keeper Boaz Myhill.
Dean Windass nearly doubled Hull's lead midway through the second half when Parlour played the ball into the 37-year-old frontman who turned and hit a clever shot from ten yards which beat keeper Andy Lonergan but came back off the post.
Moments later Forster had a great chance to grab his second goal of the afternoon as he stole the ball from Sean St Ledger just outside the box and ran in on goal, but his 12-yard shot was saved by Lonergan.
Hull did get their second goal on 70 minutes when Sam Ricketts swung a cross in from the right which found its way to Windass at the back post. He neatly headed the ball back across goal allowing Livermore to charge in and send a close-range diving header into the back of the net.