The hosts opened the scoring in the 10th minute when a long clearance out of defence was headed on by Ryan Taylor and Will Atkinson touched the ball to the advancing Nicky Law, who slammed a first time shot past Stuart Tomlinson.
And nine minutes later the home side doubled their lead with a copy book goal when they cleverly switched play from the left to the right for Danny Coid to cross and pick out Ryan Taylor whose powerful header flew over Tomlinson and into the back of the net.
Vale were then reduced to 10 men when goalkeeper Tomlinson came racing out of his area and bowled over Marcus Marshall with his challenge.
And 38 seconds into the second half, Rotherham made it three when Will Atkinson went on a diagonal run across the Vale penalty area and flicked a shot past everyone and into the net.
The fourth goal came after 69 minutes, a spectacular overhead effort from Ryan Taylor from Adam Le Fondre’s cross. And Rotherham made it five six minutes from time when Arsenal loanee Mark Randall crashed in a magnificent 25-yard angled shot from Johnny Mullins’ throw in.