One of United's Italian imports Antenucci had previously swept an Alex Mowatt cross wide, but later showed more clinical finishing to roll the ball into the bottom corner after Souleymane Doukara had found his smartly-timed run.
Doukara passed up a chance to double his side's lead on 44 minutes when he twice scuffed shots from inside of 10 yards, after Antenucci had driven forward and seen a shot deflect into his partner's path.
Hosting Rotherham also pushed hard for a goal before the break, but Ryan Hall's powerful free kick was high, while Matt Derbyshire and Lee Frecklington's tame efforts were easy pickings for Marco Silvestri.
The Leeds goalkeeper was more seriously tested by Revell on 39 minutes, having to dive full length to his right to keep out a header from the Millers target man following a Ben Pringle delivery.
Pringle's crossing continued to be a feature, but Revell nodded a few yards over the crossbar in Rotherham's bright start to the second period which also saw Silvestri punch clear a Paul Taylor free kick.
Two mistakes from Leeds allowed the home side to equalise on 58 minutes, as Frecklington drove through a weak Giuseppe Bellusci tackle to shoot at Silvestri, whose parry was bundled home by Revell for his first goal since the League One playoff final at Wembley in May.
After Revell had slid in to dispossess Tommaso Bianchi on the halfway line, the £400,000 recruit from Oldham Athletic ran with the ball unchallenged before hitting an unstoppable 25-yard drive into the bottom corner.
Adryan tried to reply in turn and forced a full-stretch dive from Rotherham goalkeeper Adam Collin with a shot bound for the bottom right corner, before narrowly missing the same post with another decent effort.
Collin was required again as Leeds pushed for a late point, getting down quickly to deny Antenucci a second and ensure the Millers a victory which takes them level with their neighbours, who are still waiting for a first win under Milanic, in the Championship table.