After a goal less first half, Sharp took advantage of poor defending from a corner to net his first goal, in his third spell with the Blades. And, after the Tangerines back-line fell to its knees, McNulty fired home a second to kill the game, and retain Nigel Adkins 100% home record.
Adkins was forced to tinker with the pre-match squad, Neill Collins (calf) and Stefen Scougall (ankle) where both substituted (due to injury) in midweek, leaving Kieran Wallace and Jamal Campbell-Ryce to deputise in their absence.
United retained plenty of possession in the first half, but struggled break down a fairly solid Tangerines defence, in the opening ten minutes their back-line where left untroubled and keeper Kyle Letheren had yet to touch the ball. It was the visitors who won the first corner of the match, 19 minutes in and McAllister's effort was enough to force Howard into a save.
At the other end, Basham headed convincingly over from a corner and Sammon's shot, unable to generate any power behind it, trickled to the keeper, before Robertson headed straight at Howard after connecting with a free-kick.
The best chance in front of goal fell to United, and it happened to be the final opportunity before referee Darren Deadman blew up for half time. Baxter supplied a weighted pass to Wallace who cut-back to Sammon, and his goal bound effort was somehow deflected over the bar.
In the opening exchanges of the second half, United were given a huge scare, after Basham was yellow carded for a foul on Potts, Ferguson's resulting free-kick bounced off Howard's left post, thankfully, this was to be a rare opportunity in front of goal for the visitors.
On 54th minute, Adams was guilty of being too generous in play, on the angle, he had the chance to shoot, but instead laid off Sharp who was quickly cut-out as a golden opportunity went begging. Campbell-Ryce danced round three defenders and his low cross found Sammon, but despite being unmarked somehow missed an almost open goal. Then in a double change, Adams and Sammon were replaced by Woolford and McNulty.
The changes brought a divine intervention, and soon, on the hour mark, the Blades broke the deadlock when McEvereley's low corner into the box found SHARP, after Basham had made space, to drive the ball at goal, Letheren got a hand to it, but was too powerful, and Sharp wheeled away in celebration, scoring his first goal in his new spell with the Blades, and in front of a roaring Kop.
Blackpool soon opened up as they were now forced to attack, rather than total defending, McEvereley made a vital block from Potts, before United doubled their lead. Down the left hand channel, a neat ball was played to Sharp who did enough to find McNULTY to control, and just before entering the 18 yard box unleashed a shot which nestled coolly into his right corner.
The goal came as a bitter blow to Blackpool, who, for all their efforts, had set up to try and take at least a point home. Woolford tried from distance, but Letheren collected at the second attempt. In the final five minutes Howard turned Potts effort round the post as Pool looked for a consolation prize.
Sheffield United: Howard, Freeman, Basham, Sharp, Baxter, Sammon (McNulty 56), McEveley, Campbell-Ryce (J Wallace 70), Adams (Woolford 56), K Wallace, Edgar. Unused: Reed, Higdon, Long, McFadzean.
Blackpool: Letheren, Ferguson, McAlister, Robertson, Potts, Cullen (Thomas 79), Cameron (Redshaw 68), Oliver (Cubero 79), Aldred, Boyce, Osayi-Samuel. Unused: Jones, Boney, Dunne, Higham.