The bottom of the division is looking increasingly congested with Cheltenham one of a number of sides whose form has picked up in recent weeks.
This was a deserved win for the Robins, who claimed the points with two second-half goals - the first of them a breathtaking strike from right-back Brian Wilson.
During the first half both sides struggled to create clear-cut chances, although the visitors almost broke the deadlock after only six minutes when Delroy Facey headed a Ritchie Partridge cross wide from only six yards out.
By then Rotherham had already been forced into a change with Northern Ireland international Colin Murdock limping out of the action to be replaced by Scott Wiseman.
Facey and Martin Woods of Rotherham both shot wide from distance but Cheltenham 's Steve Guinan also went close with a header from a John Finnigan cross.
Cheltenham felt they should have had a penalty when midfielder John Melligan went to ground under a challenge from Gregor Robertson but referee Danny McDermid was having none of it.
After the break Cheltenham stepped up the pressure and should have taken the lead during a crazy incident on the hour mark.
Striker Kayode Odejayi robbed defender David Worrell of possession then crashed a shot against the underside of the crossbar and out again. Guinan's follow-up shot was cleared off the line by Worrell then Odejayi shot wide from an even better position.
The breakthrough finally arrived on 64 minutes when Melligan's cross was cleared by the Rotherham defence but only as far as Wilson and he let fly with a thumping 25-yard strike that gave goalkeeper Neil Cutler no chance.
Cheltenham had to withstand some pressure late on with Shane Higgs making one fine save from Woods, but they made the game safe deep into injury-time when substitute David Bird broke away and scored with a heavily deflected shot from the edge of the area.