A deft, curling effort from John Cofie secured the Blades another pre-season victory.
The loan striker displayed a cool head to lift the ball over Rotherham goalkeeper Scott Shearer in what proved to be the difference between the South Yorkshire sides.
All three of Monday's signings - Hill, McMahon and Miller - were part of the squad for the short trip across the motorway but kick-off was delayed by 15 minutes due to the volume of fans entering Rotherham's gleaming New York Stadium.
The Blades, wearing the new black away kit, started brightly and created an opportunity inside a minute but Maguire's header was wide. The Millers hit back with Nardiello being put clear but Howard was off his line quickly to make a quality save. Mullins headed a corner wide soon after and then, on 13 minutes, a Pringle free-kick was deflected into the net but the effort was ruled out by an off-side.
The woodwork then got involved as the early chances continued. For the Blades, Maguire headed a Flynn corner against a post and at the other end Pringle's 20-yard free-kick struck the crossbar - both chances arriving before 20 minutes had elapsed.
Howard then had to make saves from Pringle and Ainsworth before the visitors took the lead five minutes before the interval. Tonne found COFIE, who waited patiently before curling perfectly over Shearer from the left side of the box. A second almost followed but Shearer saved a close-range header from McAllister.
Danny Wilson made glut of half-time changes but the first chance of the second period fell to the home side when Maguire was robbed by Nardiello but Odejayi was unable to capitalise. The Millers then began to exert a bit of pressure but the Blades held firm and Howard was rarely troubled.
Second half substitutions interrupted the flow of the game but Miller's first touch almost resulted in a goal, whilst Doyle shot wide as the visitors looked for a second.
Taylor fired over in the last ten minutes as the home side looked for a leveller and Quinn blocked from Pringle. The final chance, on a break, came from Quinn but Shearer tipped the ball around a post before World Cup Final referee Howard Webb's full-time whistle signalled a Blades victory.
Rotherham: Shearer, Bradley, Mullins, Sharps, Wilson, Ainsworth (O'Connor 80), Arnason (Evans 80), Noble (Taylor 63), Pringle, Odejayi, Nardiello (Agard 63).
Unused: Warrington, Revell, Rose.
Blades: Howard, Westlake, Williams (McMahon 45), Montgomery (Doyle 45), Maguire, Hill, Flynn (McFadzean 73), McAllister (McDonald 45), Porter (Cresswell 70), Cofie (Miller 74), Tonne (Quinn 45).
Unused: Long, Ironside, Philliskirk.