Born in Nervi, Gazzolo began his career on screen in 1938 starring in the comedy film The Document and became more successful after the end of World War II.

Among his most popular filmography included The Jester's Supper, Four Steps in the Clouds and The Band of Honest Men.

He even dubbed over the voices of Sam Jaffe, George Hayes, Peter Lorre, Alan Napier, Joseph Egger, Arthur Malet, H. B. Warner, Gary Cooper, Charlie Chaplin, Charley Grapewin and Fernandel in either most of or their iconic film appearances.

In Gazzolo's animated roles, he was renowned for dubbing characters in Walt Disney films such as Bashful in Snow White and the Seven Dwarfs, Dandy Crow in Dumbo, The White Rabbit in Alice in Wonderland, Archimedes in The Sword in the Stone, Jock in Lady and the Tramp, Rabbit from 1968 to 1970, Speaker of Goofy's shorts in Californy 'er Bust, Professor Owl, Ludwig Von Drake from 1963 to 1970 and Goofy from 1950s to 1960s.

Gazzolo had one son, Nando, from his marriage to Aida Ottaviani Piccolo, who was a radio announcer for EIAR.