Accornero began very early to make theater. He didn't finish university, but accepted a job from his professor, Gian Renzo Morteo. In 1981 he began an intense activity in radio prose which led him to a lasting partnership with Alberto Gozzi and with the Barlumen Institute. In those same years he was very comfortable in the role of Pieretto in Pavia's film Il diavolo sulle colline, by Vittorio Cottafavi (Cannes Film Festival, 1985). He went on and worked with Fellini (Ginger and Fred), Soldini (L'aria serena dell'Ovest), Giannarelli, Calopresti, Ferrario, Argento, Verdone, Faenza, Saura, Martone.

In the theater he worked for two seasons with Carlo Cecchi, then with Ronconi, Missiroli and many others. On television he had often been in national-popular dramas, in roles of guard but also of thief, directed by Gregoretti, Perelli, Di Carlo, Questi, Capitani, Giordana, Zaccaro, Dayan, Cavani, Frazzi and many others. In 2010 he was awarded in three festivals as best actor for Cribari's Diario di un disagiato. Among the roles he had played are those of Monsignor Angelo Dell'Acqua in the miniseries Papa Giovanni, that of Captain then Major Aloisi in the series Il Maresciallo Rocca and that of the inflexible and cynical human resources manager Guido Geller in the sitcom Camera Café [it].

• Il diavolo sulle colline, dir. Vittorio Cottafavi (1985)
• The Two Lives of Mattia Pascal, dir. Mario Monicelli (1985)
• Remake, dir. Ansano Giannarelli (1987)
• The Peaceful Air of the West, dir. Silvio Soldini (1990)
• Who Killed Pasolini?, dir. Marco Tullio Giordana (1995)
• We All Fall Down, dir. Davide Ferrario (1997)
• L'educazione di Giulio, dir. Claudio Bondi (2000)
• Sleepless, dir. Dario Argento (2001)
• It Can't Be All Our Fault, dir. Carlo Verdone (2003)
• The Best of Youth, dir. Marco Tullio Giordana (2003)
• The Voyage Home, dir. Claudio Bondi (2004)
• I giorni dell'abbandono, dir. Roberto Faenza (2005)
• The Double Hour, dir. Giuseppe Capotondi (2009)
• I, Don Giovanni, dir. Carlos Saura (2009)
• Noi credevamo, dir. Mario Martone (2010)
• The Dinner, dir. Ivano De Matteo (2014)

Animation edit

• Narrator in X-Men: Pryde of the X-Men
• Fox in The Gruffalo
• Fox in The Gruffalo's Child
• Kizashi Haruno in Road to Ninja: Naruto the Movie
• Kizashi Haruno in Road to Ninja: Naruto the Movie
• Brain in Top Cat: The Movie
• Brain in Top Cat Begins

Live action edit

• Adam Zarrow in Anesthesia
• Nickels in The Devil's Tomb
• Mika in The Captive
• Dr. Christian Keedler in Lucky
• Dr. Reinhard Winkler in 1001 Grams
• Ray Warding in Lying and Stealing
• Denis Goldberg in Escape from Pretoria
• Bill Seidel in The Mauritanian

• Sam Torpedo (2001) – radio drama – Radio 3
• La fabbrica di polli (2008) – radio drama – Radio 3

• Roberto Accornero at IMDb