Mitropoulos was born in Volos, Thessaly on August 23, 1957. He started his football career at Aris Petroupolis, a suburban team. In 1976, he transferred to Ethnikos Piraeus where he spent the next five years playing as a midfielder or, on occasion, centre-forward. In 1981, he moved on to the other Piraeus club, Olympiakos.
At Olympiakos, Mitropoulos made a name for himself as an energetic, hard-working player who would push himself and inspire his team mates. He won three league titles and two Greek Cups for the red-and-whites before moving on in 1992.
Mitropoulos proceeded to play with:
During his career, Mitropoulos participated in 477 Alpha Ethniki league games scoring 99 goals. He was capped 77 times by the National Football Team of Greece (8 goals) and was a member of the World Cup '94 squad that played in the US.