Bryan Robson's team had gone 15 games without a victory on their travels until their 1-0 success at Leicester in midweek, but they looked set to take another notable scalp once Jon Stead scored in the first half.
But Hull claimed a point after 54 minutes through Dean Windass's penalty.
The hosts squandered a handful of good opportunities to win the game after equalising, with Manchester United loan signing Fraizer Campbell particularly culpable.
But the same could be said of United, who look to be improving under Robson after a troubling run of form.
Ian Bennett, who replaced the injured Paddy Kenny in United's starting XI, could not have wished for an easier re-introduction as Hull rarely threatened in the early exchanges.
The Blades were hardly a potent attacking force in the first half either but still secured a surprise half-time lead 10 minutes before the break.
Hull's square back four took some degree of blame as the impressive Alan Quinn easily dissected Wayne Brown and Damien Delaney with a sweet pass.
Stead, on the bench against Leicester, gathered the ball inside the penalty area and powered the ball through Boaz Myhill's legs to make Robson's team talk much easier at the interval.
The United boss would not have been impressed upon his return to the dugout, though, as Hull winger Bryan Hughes headed just wide 60 seconds after the restart.
Encouraged, Phil Brown's team consolidated after a fine spell of pressure with the equaliser six minutes before the hour.
Campbell showed neat control inside United's 18-yard box and too much guile for Michael Tonge, whose clumsy foul resulted in a penalty.
Windass converted the spot-kick with the minimum of fuss.
Deficit almost became profit two minutes later when Ian Ashbee's half-volley from 16 yards was well parried by Bennett.
Campbell, who scored twice on his home debut against Barnsley on Monday, then wasted a superb chance with a wayward header following Hughes' perfect cross.
Robson's men hit back two minutes later when Danny Webber's flick was skilfully clawed away by Myhill, before James Beattie failed with a tame follow-up.
If Delaney was at fault for the Blades' goal, the Hull left-back redeemed himself late on with an excellent intervention from Webber's cross which ensured a share of the spoils.