Magnozzi was born in Livorno, and played for his home-town team from 1920 until 1930. In 1920 Livorno won the "Torneo del Sud", after which it was defeated by Inter (winner of "Torneo del Nord") in the final for the overall Italian title. The match finished 3–2 for Internazionale, with both of Livorno's goals being scored by Magnozzi. During the 1924–25 season with Livorno, he was the top scorer in Serie A. In 1930 he moved to A.C. Milan, where he served as the club's captain, and remained there until 1932, when he was sold back to Livorno. He remained there until he retired in 1936.