Mantalozis started his football career as a centre forward with a local club named Olympiakos Pasalimani. In 1943, he joined Ethnikos Piraeus where he played as goalkeeper during the late 1940s and 1950s. In 1959 he transfered to Panathinaikos as a backup keeper.
Mantalozis was capped a total of 10 times by the Greek National Football Team.
He is considered one of the top Greek goalkeepers of all-time.