The striker turned and swept home left footed past Tommy Lee in the final minute to send 1,500 travelling Millers barmy on the cold Cross Street terraces.
It was no more than an unchanged Millers side deserved, after a scrappy first half they were in total control of the second period for long intervals.
The game opened up with Dom Green setting up veteran Barry Conlon for the home side, but his 20 yard curler whistled wide of Andy Warrington's upright.
The Millers then hit back on the quarter hour when Pope fed Nicky Law, but his effort was blocked by Lee with his feet.
Warrington then misjudged a high ball into the box, and the ball fell loose to Jack Lester, but on his comeback from injury he blazed the ball over the top from eight yards out.
Kevin Ellison missed the Millers best chance of the first half, blasting over when well placed after he latched onto Micky Cummins' pass, but both teams in truth cancelled each other out.
After the break Rotherham upped their tempo with Dale Tonge coming on to replace the injured Gavin Gunning and hot shot Adam Le Fondre looked set to give the Millers the lead with 25 minutes left, but after Aaron Downes error in the area he snatched at a clear sight of Lee's goal and the 'keeper smothered his left foot shot.
Warrington was then called into action at the other end, as he tipped a first time Downes drive from 20 yards over the top.
But with the Millers pressing and home bodies looking jaded, Pablo Mills crowned a superb defensive display by firing in a low cross at the other end for Pope to control and finish off to seal the points.