Born in Milan, Campatelli debuted in Serie A at 17 years of age and played for Inter twelve seasons; in his early years he played as an offensive winger with an eye for goal; he subsequently moved to midfield and later also played as a defender. At twenty years of age he had already won a league championship and had been called up to the Italy national team by Pozzo to replace Serantoni in midfield. In 1940 he won his second title with Inter becoming the club's captain and a pillar of the team's midfield, while still maintaining his great striking ability. After taking part in the 1950 World Cup he went to Bologna where two years later he closed a brilliant career to become a coach. In his last two years at Inter he became the idol of a defender from Friuli, Enzo Bearzot, who later became the coach of the Italian team that won the 1982 World Cup.