Celtic boss Neil Lennon plans to use the defender in their crucial Champions League qualifier today.
According to the Nottingham Evening Post, though, he has agreed to let the defender return to his former club after accepting a bid.
Forest's initial offer of £1.5m was rejected by Celtic, who see Wilson as an important part of their squad.
With the defender desperate to move back south of the border, though, Lennon has agreed to let him leave for a £2.5m fee.
Lennon admitted yesterday that he was unsure of the defender's future, and it now seems that it will be with Forest, with whom he had a four-year spell before moving to Scotland in 2011.