A 48th minute header from Johnny Mullins was enough to give Harriers a deserved victory in difficult conditions at Aggborough.
Kidderminster had the better of the game and were well worth the three points which lifted them above relegation rivals Cambridge, and gives them a fighting chance of staying up.
Stuart Watkiss' men started brightly and could have opened the scoring within the first minute when Bertrand Cozic's close-range effort was saved by the foot of Shane Higgs.
Harriers also came close when Blair Sturrock volleyed wide from the edge of the box and John McGrath fired wide with his wrong foot, while Cheltenham's Brian Wilson almost sent a header inadvertently flying past his own keeper.
The Robins did not look like a side pushing for the play-offs, with Steve Guinan and Steven Gillespie both wasting decent first-half oppurtunities.
The second half belonged to Harriers and Mullins' header from a Dean Keates corner three minutes in was just reward for another impressive performance from the on-loan Reading defender.
Harriers could have made sure of the result when Chris Beardsley earned space in the Cheltenham box, but just as he was poised to shoot, team-mate Sturrock stole the ball off his toe and rolled a feeble effort wide of the far post.
Ultimately it took the heroics of Kidderminster keeper John Danby to safeguard the points with a brave block at the feet of Gillespie and an acrobatic tip-over to keep out a Gavin Caines header.
After throwing away a lead in their last three games, Harriers produced a battling backs-to-the-wall performance, with Mullins and Mark Jackson outstanding in central defence, midfielder McGrath covering every blade of grass, and Beardsley working hard to hold the ball up and defend from the front.