After their win at Grimsby, Ian McParland's men were looking to achieve back-to-back successes for only the second time in the year but their hopes began to recede with a goal for the visitors as early as the fifth minute.
Rotherham had already appeared somewhat fortunate to escape a penalty concession when Delroy Facey was sent sprawling in the box but Premier League referee Mike Dean waved County's claims away.
The Millers immediately countered and an immaculate throughball by Danny Harrison set up their opening goal.
He fed Reuben Reid who cut across Mike Edwards before shooting low just inside Kevin Pilkington's left-hand upright. The Notts goalkeeper appeared to get a hand on the ball without being able to prevent it crossing the line.
Notts had plenty of possession thereafter but visiting goalkeeper David Stockdale was given an easy time of it until the 27th minute.
Then Notts midfielder John Thompson burst into the Rotherham penalty area and hit a low shot on target which the diving Stockdale turned round his post for his best save of the match.
The issue was settled in the first 10 minutes of the second-half though when Rotherham demoralised Notts with two quick strikes.
First, on 47 minutes, Mitchel Hanson was caught in possession, Jamie Green picked up the loose ball, fed it to Reid and his low cross to the back post was swept in by Drewe Broughton from no more than four yards.
Rotherham's Andy Nicholas was a threat all through with his long throws, one of which produced Rotherham's third goal on 53 minutes. Notts failed completely to cut out the danger and Micky Cummins latched on to the ball and crashed it into the top corner.
The game was all over as a contest and Notts lacked both the invention and the firepower to get back into it.
Admission for only £5 had attracted the biggest gate of the season but fans were streaming home long before the finish.
Those who stayed behind were from Rotherham who had paid the full £20 admision price for away fans.