Sky Sports understands that Darren O'Dea is set for a summer move back to the Chamionship.
O'Dea spent the whole of last season on loan at Leeds United and has previously enjoyed stints at Reading and Ipswich.
Celtic had an option to keep him for another year, but following talks the two parties have agreed that he can leave on a free transfer.
"I'm very happy," said O'Dea, who is currently with the Repubic of Ireland squad ahead of Euro 2012.
"I spoke to Peter Lawwell (Celtic chief executive) and fair play to him. I've been leaving for long enough and it was about time it was official.
"Fair play to Peter for cutting ties. It lets me get on with my career; this has been happening for the last two and a half years anyway.
"I've had a great time at Celtic and have a lot of friends there so it was important for me that I left properly. He's done that and given me the chance to do that, so I've nothing but admiration for the club and I wish them all the best."
Sky Sports understands that a host of clubs in England's second tier are keen on securing his signature.
Bolton, Burnley and Peterborough are amongst the names reportedly keeping tabs on his situation.