Originally from Brescia, Beccalossi started his football career with his hometown club in 1972, and later became a favorite of the Inter Milan fans, where he spent the majority of his career, from 1978–79 to 1983–84, frequently wearing the number 10 shirt. He donned the Inter jersey in 216 games, scored 37 goals and helped the team win a Serie A Championship (1979–80, scoring 7 goals) and a Coppa Italia (1981–82). Together with Inter centre-forward Alessandro Altobelli, Beccalossi formed one of the longest standing offensive partnerships of Serie A's recent history. They initially played together at Brescia and later became the team's leaders at Inter from the late 1970s to the mid-1980s, while they were supported defensively by Gianpiero Marini, Gabriele Oriali, and Giuseppe Baresi.