Theodoridis started his career at the academies of AEK Athens and was promoted to the men's team in 1969 with the renewal of roster attempted by the then coach, Branko Stanković. He was a central defender unusual for the time, since he was good with the ball at his feet and had good positioning, resulting playing also as a right back.
He won with AEK 3 Greek Championships. In the summer of 1978 he moved to Olympiacos, where he played for one season, before he closing his career at OFI in 1980.