Roberts, 21, was placed on the transfer list at Gresty Road at the end of last season and has joined the Glovers on loan for the rest of the campaign.
"We are very pleased to get Gary in. He is only 21 but he's been around quite a while now," assistant-manager Steve Thompson told the club's official website.
"He's not 100 per cent fit yet, but he has already shown this week that he is a very cultured player who is good on the ball, aggressive and makes good runs. He will be a very valuable acquisition for us."