The Blades made it five wins on the bounce and in the process recorded a first league double of the season.
United were good value for Bramall Lane victory and moved above Bristol City - the visitors.
John Brayford's first goal for the Blades set the scene, whilst Ryan Flynn and Jose Baxter (penalty) contributed to the goal difference column in the second half.
Despite the victory in midweek, chief Clough again rotated, making four changes. Brayford, Murphy, Baxter and Scougall all started with Hill, Porter and Paynter dropping to the substitutes' bench - McGinn missed out due to injury.
Kick-off confirmed that United had also reverted to a 4-4-2 system with Scougall and Baxter the front two. United were forced to kick towards the Kop in the first half and the game's opening chance was a long-range shot from City's Elliott, which was well wide, before the Blades began to assert themselves on the visitors.
Murphy almost beat goalkeeper Moore in an aerial challenge from a deflected Scougall shot which ballooned up and then glut of corners kept Bristol City on the back foot. The crowd first got off their feet, however, on 17 minutes when a marauding run from Maguire started on the halfway line and ended at the six yard box when his shot was blocked by a combination of Emmanuel-Thomas and El-Abd.
City did manage to take the sting out of United's early onslaught, whilst a number of under or over hit passes prevented the home side from gaining further momentum.
As half-time approached, Howard raced off his line and collided with Baldock from El-Abd's pass but Barnett did nothing with the rebound, just moments before the Blades snatched the lead. Another Baxter corner, this time from left, saw Maguire get the slightest of touches and BRAYFORD was ideally placed to slot home at the back post.
Like the end of the first half, Murphy and Baxter had swapped roles at the start of the second period and the Blades were still the more dominant force. Harris fired a free-kick which was saved before the lead was doubled on 58 minutes.
Murphy's direct running was causing major problems for the visitors and he was heavily involved in the second goal. He easily turned away from Osborne and proceeded to the edge of the box before laying off for FLYNN to fire across Moore, the ball finding the bottom corner of the net.
Coady and the industrious Flynn also went close before Clough made United's 3,000th substitute in league football - Hill replacing Harris. Moments later, United added a third goal was added, from the penalty spot.
Maguire and Scougall were involved before Osborne stopped Flynn's run unfairly, referee Duncan pointing directly to the spot. Before BAXTER drilled home the penalty, City made a double change and after the goal Flynn was withdrawn, to a round of applause, with Davies taking over for a home debut.
United's last change was Paynter for Murphy, with the Scotsman receiving a standing ovation for his efforts. A rare City attack saw Howard comfortably save from El-Abd but the closing minutes were purely incidental as the points were in the bag, although Scougall's effort from close range was saved by Moore.
As injury-time approached Howard protected his clean sheet with a double save - from Elliott and Baldock - before Barnett fired over and three added minutes passed without major incident before Blades fans could enjoy their weekend.
Blades: Howard, Harris (Hill 67), Brayford, Maguire, Flynn (Davies 71), Doyle, Baxter, Collins, Coady, Scougall, Murphy (Paynter 77).
Unused: Porter, Miller, Long, Kennedy.
City: Moore, Williams, Flint, Elliott, Baldock, Emmanuel-Thomas (Burns 76), Cunningham (Pearson 69), El-Abd, Pack (Reid 69), Barnett, Osborne.
Unused: Fielding, Moloney, Bryan, Gillett.