The 29-year-old defender, who began his career with the U’s back at their old Layer Road ground, has agreed a two-year contract.
“I’m really pleased to be back after a few years away,” he told the club website.
“They gave me my first opportunity and I am chuffed to be back to play my part in moving the club in the right direction.
“It is a massively different club, with much better facilities and from when the manager told me he wanted me to come and sign for the club, it was a no brainer for myself.
“I knew the club quite well anyway and knew it was a chance to come back to the same set of supporters who had backed me so well.
“I’ve always kept an eye on the club since leaving, and I’ve always had a soft spot for the U’s.”