Josh Thompson, who joined Celtic after trials at Manchester United and West Bromwich Albion, played 21 times for the club.
The central defender left for Rochdale on loan and went on to play for clubs such as Peterborough United, Portsmouth and Colchester United.
His career was ultimately cut short due to injury problems.
Now, Thompson is back at Stockport County, the club he signed for Celtic from, where he is helping players recover from injuries.
The club announced his new role on social media.
A post on the club's X account, formerly known as Twitter, said: "We are delighted to announce that former County defender Josh Thompson has returned to the Club as our new First-Team Head Physio.
"Welcome back to Edgeley Park, Josh."