He follows Eli Phipps who also signed for Colchester from Cardiff City this week.
"I had a chat with the manager at Cardiff and there wasn't a way through for me there," he told BBC Essex.
"I'm here to play first team football as anything else would be a backwards step.
"I was on loan at Newport last season and what is there compared to the facilities here is much better with the training ground and the stadium"
Cardiff City said
"We’d like to thank Tommy for his time with the Bluebirds and wish him the very best of luck for the future."