Tonge, 32 who made almost 300 appearances for the Blades, having come through the youth ranks, was released by Leeds United last summer and has signed for Stevenage on a free transfer.
The midfeilder told stevenagefc.com; "I'm delighted, I jumped at the chance to play some football, I'm very impressed, we've got a good group of players, a good manager and are trying to play the game in the right way."
He could make his debut at Fratton Park tomorrow night as his new side head to Portsmouth.