The Blades remain among the division's frontrunners after another home victory.
Chris Basham scored the all-important goal early in the second half, heading home a John Fleck cross.
Sharp returned to the starting XI and captained the Blades. Clarke and Freeman also started. Coutts missed out, suspended after accumulating five cautions, whilst Baldock picked up an injury in the previous game and Donaldson dropped to the bench. Hanson was fit again and amongst the substitutes, as were Lafferty and Brooks after international duty.
It appeared that the visitors had matched United in formation in the opening exchanges and chances were sparse. The preferred route for the Blades was down the left in the first 15 minutes, with Stevens and O'Connell heavily involved.
O'Connell almost attached himself to Basham's deflected cross, which paved the way for a succession of corners but despite the Blades getting on top, Bialkowski remained untested.
Ipswich changed their formation midway through the half and their first opportunities came just after the 30-minute mark. Blackman was forced to push away Waghorn's half-volley after Carter-Vickers failed to clear and from the resulting Ward corner, Knudsen headed over.
Soon after McGoldrick poked wide follow an attack down the right but more concerning was that Freeman stayed down in the penalty area and was stretchered off after treatment. Wright was the replacement.
Bialkowski was worked as half-time approached, he punched away a Duffy cross and then saved the blushes of defender Knudsen, who cut out Sharp's low cross - the ball was heading into the goal before the 'keeper's intervention.
United won an early corner in the second half and were quick to get on top, emphasised by the opening goal on 49 minutes. Clarke found Fleck's run down the left and from the midfielder's cross, BASHAM arrived unopposed at the back post to head home.
There was an immediate opportunity for Ipswich to level with their closest effort but from Nydam's pass, Waghorn cut inside and curled his effort against the crossbar. The opposite crossbar was rattled six minutes later when Clarke's half-volley struck the woodwork.
Waghorn linked up with McGoldrick but shot wide and Celina, on as a substitute, saw his first touch, a header, sail over the crossbar. Brooks was introduced for the Blades, taking over from Sharp - Basham claimed the captaincy.
The first contribution of Brooks was to cut in from the left but he was unbalanced as he shot wide and then, from a Duffy cross, Clarke's placed header was saved by Bialkowski. The next contribution from Duffy was to track back and prevent Knudsen getting in. It earned the attacking midfielder an ovation.
Ipswich became more frantic late on and three minutes of added time saw the visitors on the attack. Blackman punch away a Celina free-kick and Knudsen launched a couple of long throws but the Blades comfortably hung on for three more points.
Blades: Blackman, Stevens, Fleck, O'Connell, Basham, Lundstram, Clarke, Sharp (Brooks 68), Carter-Vickers, Freeman (Wright 40), Duffy (Lafferty 86).
Unused: Moore, Donaldson, Hanson, Carruthers.
Ipswich: Bialkowski, Iorfa, Knudsen, Chambers, Webster, Skuse, Waghorn, McGoldrick (Celina 72), Ward, Nydam (Sears 72), Kenlock (Downes 58).
Unused: Gerken, Smith, Spence, Connolly.