Bini was born in San Daniele Po. After spending his youth career with Cremonese (1966) and Inter (1968–71), he also went on to represent the Inter senior team for fourteen seasons during his club career. He joined the first team during the 1971–72 season, making his debut on 7 May 1972, in a 0–0 away draw against Sampdoria; he remained with the club until 1985, later being named the team's captain in 1978, and wearing the armband for the next seven seasons, until he left the club. During his time in Milan, he made 343 appearances (233 in Serie A), scoring 13 goals (seven in Serie A); he won a Serie A title in 1980, and two Coppa Italia titles, in 1978, and 1982, also reaching the semi-finals of the 1980–81 European Cup, during which he scored a goal against Real Madrid. After struggling with injuries and competing with Riccardo Ferri for a place in the starting line-up during his final season with the club, Bini later joined Genoa, where he remained until his retirement in 1988, spending the last two seasons of his career in Serie B.