Magnozzi was born in Livorno, for whose team he played until 1930. In 1920 Livorno won the Torneo del Sud, after which it was defeated by FC Internazionale (winner of Torneo del Nord) in the final for the Italian overall title. The march finished 3-2 for Internazionale, both Livorno goals scored by Magnozzi. In 1924-1925 he was the top scorer of the Serie A. In 1930 he moved to AC Milan, where he remained until 1932, when he was sold back to Livorno. He remained there until he retired in 1936.
He was a member of the Italian team, which won the bronze medal in the football tournament.
As a football coach, he led Milan, Lecce, AEK and Livorno.