Cisse was booked for his extravagant goal celebration
Djibril Cisse's first-half header eased Sunderland's relegation fears and kept Hull very much in the dogfight.
The opening period was scrappy but Danny Collins flicked on Andy Reid's cross in added time and Cisse finished at the far post.
Kenwyne Jones was denied a goal for offside as the Black Cats had the bulk of possession after the interval.
The home side spurned several chances with substitute Daryl Murphy striking a post and Hull could find no way back.
The omens before the match were not good for either side, with Sunderland having lost their last four matches and Hull having achieved only one victory in their last 16.
But the opening exchanges were open and entertaining as both sides created chances.
Sbragia delighted with 'precious' three points
Boaz Myhill twice had to be alert in the Hull goal to deny Cisse, swooping on the ball fractionally before the striker to collect Grant Leadbitter's neat through ball and then dashing out of his area moments later to head a long ball clear with the Frenchman again bearing down on goal.
Geovanni's dipping volley was just too high for Hull and he later crossed for Kevin Kilbane, whose diving header was smartly pushed away by Craig Gordon.
But the half soon descended into a patchy affair with few moments of genuine quality.
However, in the final minute of stoppage time, Cisse was ideally place at the far post to nod home from inside the six-yard box, although Hull followers may argue he was in an offside position.
Cisse might have added another in the first minute of the second period when he raced through, only for Myhill to block his low shot with his legs.
Sunderland continued to press and were unfortunate when Jones was just ahead of the final defender when he headed in from three yards, but at the other end George Boateng launched a ferocious piledriver from 20 yards that swerved narrowly wide of the upright.
The home side remained generally the more dangerous, with Jones glancing a header inches wide before Reid, not a man renowned for rapid bursts forward, surged clear but spooned a shot over under pressure.
Brown heartened by Hull display
Caleb Folan headed agonisingly wide as Hull sought an equaliser late on, but it was all in vain.
When Sunderland secured a stunning 4-1 win at the KC Stadium in December, Hull were comfortable in seventh place.
Now, with three of the top five to play in their final six matches, including Manchester United on the final day, the remainder of the season is going to be a test of their collective nerve and belief.
Sunderland manager Ricky Sbragia: "We came under a lot of pressure but both defences were difficult to breach.
"I don't care if our goal was offside, we had a bit of luck but had a number of chances.
"It was a vital win for us and overall I think we deserved it."
Hull manager Phil Brown: "We deserved something from the game.
"I questioned the commitment of the players last week but we certainly turned up this week.
"When we play as we did in this match, I do not fear any team. We put in a shift and when we do that we always have a chance.
"They scored after 47 minutes or so just before half-time and that is disastrous timing from our point of view."
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