He began his career in the North American Soccer League and finished it with PAOK Thessaloniki in Greece.
Apostolidis lead the NASL in goals in 1971 and later earned six caps with the Greece national football team.
Apostolidis attended University of San Francisco where he played on men's soccer team under coach Stephen Negoesco from 1964 to 1967 and The Greek Americans A.C. in the San Francisco amateur soccer league His senior year, he was selected as a first team All American.
The move paid off immediately for the Tornado as Apostolidis led the league in scoring, tying with Carlos Metidieri for the points lead.
In 1971, he won the title and finished fourth in the league in goals, but left the NASL at the end of the season to return to Greece.