Emmanuel was with West Ham United as a youngster before joining Ipswich Town’s youth set-up, going on to make 29 first-team appearances.
He has also had loan spells with Crawley Town, Shrewsbury Town and Rotherham United, where he won promotion from League One.
After leaving Ipswich, he played for Bolton Wanderers, Hull City and Grimsby Town before playing for Carlisle last season.
McCann said: “I know exactly what he is capable of. He’s in really good condition. He adds competition to the defensive area.
“He’s a good character and has very good attributes with his pace, power and is strong in duels, so he ticks a lot of boxes in what we like.”
