Russo was raised in Rosebank, Staten Island. He claims that he has Mafia connections and that his uncle was a soldier in the Gambino crime family. There are claims that the Gambinos persuaded Francis Ford Coppola to cast Russo as Carlo Rizzi in the 1972 movie The Godfather. According to Russo, his father was a longshoreman and a musician who worked at the Brooklyn waterfront who was ashamed his only son was crippled from polio and refused to acknowledge him during his early childhood. He suffered from a "gimp arm" as a result of the disease.
After reprising the Rizzi character in a brief flashback scene at the end of The Godfather Part II, Russo went on to act in more than 35 movies, including The Freshman, Super Mario Bros., Any Given Sunday, and Seabiscuit.
Russo claims that he started a fledgling career in organized crime working as an errand boy and mob associate for Frank Costello as an adolescent but later abandoned the dangerous and volatile lifestyle of organized crime.
In his 2006 book Supermob, investigative reporter Gus Russo (no relation mentioned) writes that Gianni Russo secured his role in The Godfather by acting as an intermediary between Paramount Studios and New York Mafia don Joe Colombo Sr., whose Italian American Anti-Defamation League had shut down early production of the film in Manhattan. Colombo met with the film executives, who then hired Russo to play Carlo after Russo had earlier threatened Marlon Brando, who thought he was acting and was so impressed that he changed his objections and had him hired.
Russo claims that he has personally known three popes, five United States Presidents and every Mafia boss in the United States. He also claims to have had romantic trysts with Marilyn Monroe, Zsa Zsa Gabor and Liza Minnelli. Over the years since the beginning of his career, he has owned a Las Vegas restaurant called Gianni Russo's State Street, dated Dionne Warwick for more than a decade and has successfully defeated 23 federal criminal indictments on a variety of charges stemming from alleged organized crime associations.
Russo is also an accomplished singer. In 2004, he released a CD called Reflections that pays homage to Dean Martin and Frank Sinatra.