Kelechi previously worked with Celtic manager Brendan Rogers at Leicester City, and the manager is enthusiastic about the reunion.
"Kelechi is an extremely talented player with great ability, athleticism, and a strong work ethic," Rogers said.
"He has valuable experience and is currently in his prime, making him a great addition to our team. I'm confident he will make a significant contribution to the team," Rogers added.
Kelechi has signed a 12-month contract with Celtic, with the option to extend for another year.
