Hunt, 37, made more than 100 appearances for Bolton before going on to feature for the likes of Bristol City, Preston North End, Accrington Stanley and most recently Darlington.
As well as playing for the Robins, Hunt will be joining Michael Clegg's backroom staff as a first-team coach.
Manager Clegg said: “In football, you always need good people around you. Me and Nicky have been all through school together and he is a massive addition to the coaching staff as he has just completed his A-license.
"He will also be part of the first-team squad and be available for selection for games. We have always wanted to work together so the timings were just perfect. The lads know Nicky well as he has been around us for 18 months now, coming to the odd game and training night."