Volonté was born in Milan, and graduated in Rome in 1957. He had a brief career as a television and theatre (Shakespeare, Goldoni) actor, before concentrating on his film career.

He made his debut in 1960 in with Sotto dieci bandiere, directed by Duilio Coletti. Just four years later, Volonté played "Ramón Rojo" in A Fistful of Dollars (1964), and "El Indio" in For a Few Dollars More (1965), both for cash reasons as he did not consider either role seriously. Both films were directed by the then-unknown Sergio Leone, and Volonté's roles in them would bring him his greatest recognition from American audiences.

His performances as memorable but neurotic characters, together with the unexpected, worldwide success of the films, gave him international fame. Volonté had already played comedies, including A cavallo della tigre (1961), by Luigi Comencini, and confirmed his versatility in L'armata Brancaleone (1966). However, he found his main dimension in dramatic roles for Banditi a Milano (1968), by Carlo Lizzani, Sbatti il mostro in prima pagina (1972) by Marco Bellocchio, La Classe operaia va in paradiso (1972) by his friend Elio Petri and Il sospetto (1975) by Francisco Maselli.

Hommage to Gian Maria Volonte by Reginald Gray. (seen in his role as Carlo Levi in "Christ Stopped at Eboli".) In 1968 he won a Silver Ribbon as best actor for A ciascuno il suo, also directed by Elio Petri. Volonté received the same award for two other performances: Petri's Indagine su un cittadino al di sopra di ogni sospetto (1971, winner of an Academy Award as best foreign film), considered by many to be his finest; and in Opera al nero (1989). In 1983 he won the award for Best Actor at the 1983 Cannes Film Festival for La Mort de Mario Ricci. Four years later, at the 37th Berlin International Film Festival, he won the Silver Bear for Best Actor for Il caso Moro.[1] In 1990 he was declared best European actor for Porte aperte. In 1991, at the Venice Film Festival, he won a Golden Lion for his career as a whole.

Volonté also played numerous roles outside Italy.

Companion of Italian actress Carla Gravina for almost 10 years, they met when they played Romeo and Juliet in the theatre in 1960. The two had a daughter Giovanna, born in the early 1960s.

The actress Angelica Ippolito was his companion from 1977 until his death in 1994.

He died from a heart attack in 1994 at Florina, Greece during the filming of Ulysses' Gaze, directed by Theo Angelopoulos. His role in the film was recast to Erland Josephson.

As he asked, Volonté's final resting place is a small cemetery on the Sardinian island of Isola della Maddalena.