Danny Livesey pounced with seconds to spare to send Carlisle joint top of the League One table.
The big defender volleyed in from 12 yards for his second goal of the season after the luckless Shane Duff had blocked Marc Bridge-Wilkinson's drive.
Cheltenham had frustrated the home side after the break and were left with little time or energy to hit back.
The Robins had shaded the first half, but despite forcing five corners in the opening half hour, they found Carlisle's defence tough to break down.
The Cumbrians gave a debut to on-loan Chelsea defender Harry Worley, but the teenager suffered a torrid game and was booked for petulantly kicking the ball away.
He was then lucky to avoid a second yellow card for an elbow on Paul Connor and the hapless loanee was substituted at half-time before he could get himself sent off.John Finnigan and Andy Lindegaard both went close with long-range shots in the first half, but that was as good as it got for the sparse away following who had come up from Gloucestershire.
With 20 minutes to play a left-foot thunderbolt from Danny Graham kick-started the late Carlisle onslaught.Shane Higgs made a great save from Graham but was left helpless just minutes later when Michael Townsend sliced Paul Arnison's cross over his own bar from four yards out.
Substitute Arnison, on for Worley, should have opened the scoring but side-footed inches wide when he and Keven Gall got in each other's way.
With ten minutes to go, Arnison delivered a great deep cross for Graham, but he could only head over from close range.
Striker Joe Garner almost headed in after a corner, before Townsend made a great last-ditch tackle to stop Carlisle's record signing from firing in.