Former United trainee James Chester volleyed Hull into an early lead and it was 2-0 to the home team inside 13 minutes following the scrappiest of goals as a series of scuffed shots and attempted clearances ended with David Meyler's weak strike taking a deflection off Jonny Evans and bobbling past a wrong-footed David de Gea.
United's response was outstanding, though, as Chris Smalling headed in after 19 minutes and Wayne Rooney equalised with a thunderous volley from outside the area seven minutes later.
Alex Bruce almost restored Hull's lead in the second half as he crashed a header against the crossbar, but instead it was the Red Devils who grabbed the decisive fifth goal on 66 minutes when Chester headed Ashley Young's right-wing cross past his own goalkeeper.
Hull piled on the pressure in the closing stages but United clung on for a third straight league win, despite Antonio Valencia getting sent off in the 90th minute for a second bookable offence.
Darren Fletcher was fit to make a first start in 12 months but it was unchanged Hull who scored with the first chance of the game, Jake Livermore and Ahmed Elmohamady having earned an early corner.
Tom Huddlestone delivered the ball into the box where Alex Bruce got above Patrice Evra to head towards the far post.
Danny Welbeck was slow to come off the line but Chester was one step ahead, advancing to volley first time into the roof of the net.
United had been caught cold and it got worse in the 13th minute. Meyler was the man who drove Hull into the penalty area and stayed up to collect Yannick Sagbo's cutback across the box.
His first connection was wayward but Evans allowed him a second chance with a sloppy clearance that came back to the Irishman.
The resulting shot would not have troubled De Gea but Evans again intervened, wrong-footing the Spaniard and turning the ball into his own net.
An apparent groin injury to Rafael gave David Moyes a chance to change things, and he made an aggressive move in sending on Adnan Januzaj.
He had an almost immediate impact, winning a 19th-minute free-kick from which United scored.
Rooney provided the hanging cross from the right and Smalling produced a clinical header that nestled inside the far post.
United, almost immediately, regained confidence and only a superb save from Allan McGregor stopped Tom Cleverley finding the top corner with a 20-yard curler.
The pace did not relent and, with 25 minutes gone, Rooney netted the pick of the day.
He controlled Evans' long ball effortlessly with his back to goal before flicking an overhead pass to Welbeck.
When it came back to him, via a combination of Welbeck and Curtis Davies, the England striker took another deft touch before crashing home a fierce 30-yard volley.
Steve Bruce had to reshuffle at the interval, Steve Harper on for McGregor and Robert Koren replacing Meyler.
But the hosts once more came out brightly, Sagbo working De Gea on the turn and Davies glancing a header wide from Huddlestone's corner.
Hull turned the screw again either side of the hour mark, Sagbo tripped by Valencia as he surged towards goal and Alex Bruce's header coming back off the frame of the goal.
Having weathered that storm, United promptly scored on the counter in the 66th minute.
Rooney started the move in midfield and hoped to finish it after Young had beaten Maynor Figueroa on the wing. Instead, it went down as an own goal as Chester nodded into his own net.
In the 87th minute Sagbo's determination yielded a good chance for Danny Graham to equalise but his header lacked conviction.
Valencia's red card gave Hull a sniff in extra-time but De Gea's block off Chester ensured United held out.