The 37-year-old set up the equaliser for Lee Ridley - the full back's curler was his first goal for the club - and then slid home the winner himself after good work by David Hutton.
It was a swift reversal in fortunes with the Robins outplayed in the first half by an impressive Grimsby who broke the deadlock after 35 minutes with a brilliantly worked goal scrambled in by Barry Conlon after Peter Sweeney and Adam Proudlock had sliced open the defence.
Conlon should have scored after five minutes but headed straight at keeper Scott Brown with the goal gaping.
Oliver Bozanic rattled the crossbar for Cheltenham after the interval while Ridley came close to adding a second, while Elvis Hammond spurned a number of chances.
And Conlon nearly rescued a point in the final minute but dragged his shot wide from 10 yards.