In 1965 he graduated at the Accademia Nazionale di Arte Drammatica Silvio D'Amico[1] and then began performing at the Teatro Stabile d'Abruzzo, which marked the beginning of his long career as a stage actor.

In the 1970s, he acted in the science fiction-drama miniseries Gamma as well as the detective fiction show La donna di picche, the politically-tinged crime film Chronicle of a Homicide, and more.

[2][3][4] He is also renowned for dubbing Jim Broadbent, Colm Meaney, Richard Dreyfuss, Ken Stott, Martin Sheen, John Heard, Robert Duvall, Richard Jenkins and Kurt Russell in some of their movies.

[5] Some of the Italian dubbing roles that Valli is best known for includes Ghostface from the Scream film series and Horace Slughorn from the Harry Potter franchise.

In animation, Valli dubbed Rex in the Toy Story film series and Monsters, Inc., Gobber the Belch in the How to Train Your Dragon franchise, Pops in The Secret Life of Pets franchise and Merlin Ambrosius in Tales of Arcadia; he also took over as Bender's Italian voice in Futurama starting from season 8.