A native of Padua, Cappello began his career with Padova. After spending two seasons with the club in Serie B, he landed in Serie A with Milan in 1940. In the three seasons at Milan he was always the second leading scorer and unfortunately Milan was not a major title-contender at the time. After the war he went to Bologna where he played for ten straight seasons. He scored 80 goals in 245 games leaving a mark on the fans not to be forgotten. In his last two seasons he played for Novara in Serie B. In 1958, when he was still playing with Novara, he decided to retire having reached the age of forty.