Nick Fenton almost took advantage of a woeful start by the home side when he forced Mark Goodlad to save from 10 yards after heading Michael McIndoe's left sided cross towards goal.
Vale eventually found some sort of rhythm after 15 minutes when Jeff Smith's long looping cross found Michael Cummins lurking at the back post but his effort lacked direction and went over the crossbar.
Doncaster poured forward again when a sweeping pass was headed on by McIndoe but good defensive pressure denied Paul Heffernan any room to force power into his tame header.
It was the Valiants who opened the scoring after half an hour when Mickey Bell's free-kick was flicked on to Andy Warrington's left post by Billy Paynter and instinctively poked home by Nathan Lowndes.
An action packed end to the half saw Martin Foyle's men piling on the pressure, but despite both Cummins and George Pilkington having shots on goal, their lead remained slim.
Vale doubled their tally almost immediately after the break when a poor clearance fell to Tony Dinning on the edge of the box.
After having his first effort blocked, the midfielder made no mistake with the second, firing it into Warrington's bottom right corner.
Doncaster were presented with the perfect opportunity to get back into the game when a reckless challenge by Steve Rowland earned him a second yellow card in the 56th minute.
A weakened home defence was tested straight away when McIndoe's whipped cross was directed towards goal by Ricky Ravenhill but an outstretched Goodlad saved brilliantly.
Despite being a man down, Vale continued to attack and almost sneaked a third when substitute Lee Matthews set up Smith in the 78th minute but the shot rocketed over the crossbar.