Sol Campbell has been given the green light to resume his career after finally reaching agreement with former club Notts County.
Campbell left the League Two club five weeks into a five-year contract in September after citing his desire to play at a higher level.
Professional Footballers' Association chief Gordon Taylor has now revealed that Campbell and County have now reached an agreement to release the former England international's registration.
"Sol Campbell is now a free agent," Taylor told BBC Sport.
"His contract dispute has been resolved and he is free to pursue football in the January transfer window. He can sign for any club he wants now."
The 35-year-old defender has been strongly linked with a move to Championship leaders Newcastle United when the transfer window reopens in January.
Campbell has been training with former club Arsenal since leaving Meadow Lane after making just one first-team appearance.