Bossi joined FC Basel's first team for their 1940–41 season under head coach Eugen Rupf.
Bossi played his domestic league debut for the club in the away game on 8 September 1940 as Basel won 3–1 against Fribourg.
[3] He scored his first goal for his club on 27 October in the home game in the Landhof as Basel won 4–3 against local rivals Old Boys.
[4] Bossi scored his first league goal for his club on 22 December as Basel won 2–1 in the return game against Fribourg.
On 31 August 1941 in the first league game against SC Juventus Zürich their striker Alex Mathys scored seven goals as Basel won by 10–1.
Basel won the 2nd leg at home at the Landhof 3–1 to achieve Promotion, Bossi ended his active football career.
[9] Bossi made his debut for the Swiss national team on 3 December 1933 in the Stadio Comunale Giovanni Berta.