Bellini is a one-club man; he spent his entire professional career with Atalanta, and currently holds the record for the most appearances in the club's history (435).

Born in Sarnico, Province of Bergamo, Bellini played his first league match on 11 April 1999 for Atalanta, at that time in Serie B.

In the 2009–10 season, Bellini played as left-back, while Thomas Manfredini, Paolo Bianco, Leonardo Talamonti were used as central-defenders.

[2] On 8 May 2016, Bellini scored in his final game, a 1–1 Serie A draw against Udinese at the Stadio di Bergamo.

Along with Cesare Natali, his teammate at Atalanta, Bellini was called up to the Italy under-21 side for the 2002 UEFA European Under-21 Football Championship.