After a poor end to last year that saw them plummet down the League Two table, this was the ideal start to 2018 for the Boro, who came back emphatically after falling behind very early in the piece.
Cheltenham led inside 90 seconds when Brian Graham found Mohamed Eisa in space and the Robins’ top scorer was allowed to wander towards the area before scoring at the near post.
But Stevenage equalised halfway through the first half as Scott Flinders kept out Ronnie Henry’s deflected cross, only for Matt Godden to turn in the rebound.
The Boro then went ahead when Pett beat a hesitant Flinders to a loose ball before rolling into an empty net via the inside of the post.
The hosts had a two-goal cushion when Danny Newton slotted home after not being closed down and Pett added his second of the afternoon with two minutes left.
Watford are being linked with a summer swoop for Werder Bremen's Sweden international left-back Ludwig Augustinsson.
West Ham are reportedly set to pull out of their plan to sign central defender Alfie Mawson from Swansea this summer.
Brighton have been linked with a swoop on League One Sunderland for the signature of goalkeeper Jason Steele.