Former U's boss Lambert told the club's website: "I signed him at Colchester and he had a brilliant season.
"He is someone who will hopefully benefit the team with his wide range of passing and I'm delighted."
The former Manchester United trainee joined Colchester from Blackpool in July and went on to score on his debut, the 7-1 thrashing of City on the first day of the season.
He struggled to get back into the side after a rib injury in December but scored three goals in 21 games for the U's.
Lambert has already added midfielder Andrew Crofts and defenders Steven Smith and Elliott Ward to his League One title-winning squad.
Source: BBC Sport
Source: BBC Sport