Known for his distinctive, gravelly voice, he was often cast as villains, including Moe Greene in The Godfather (1972) and his Primetime Emmy Award–winning role in The Famous Teddy Z. Rocco did a significant amount of voice-over work later in his career.

[7] In January 1960, Petricone was one of 28 persons indicted by a Middlesex County grand jury in a gambling case,[8] and in September 1961, he was arrested along with James McLean and others on charges related to an assault on the owner of a diner in Somerville, and the wrecking of his establishment, the previous August.

[9][10] According to organized crime turncoat Vincent Teresa, Rocco was a hanger-on with the Winter Hill Gang of the Boston area.

[10] Petricone and McLean were released after a grand jury found a lack of evidence,[13] but both served a prison term for the diner wrecking.

Greene's character represented the top Jewish mobster in Las Vegas; although he sought an Italian role, director Francis Ford Coppola remarked "I got my Jew!"

[1] The same year, Rocco returned to the Boston area to play a bank robber in the film The Friends of Eddie Coyle.

[16] Another Winter Hill Gang member who met with Mitchum was Johnny Martorano, who had murdered Billy O'Brien, a low-level gangster.

In the period 1989–90, Rocco was a regular on the television comedy series The Famous Teddy Z as Al Floss, a Hollywood talent agent.

Rocco had a recurring voiceover part in the long-running animated series The Simpsons as the head of Itchy and Scratchy Studios, Roger Meyers Jr.

He did further voice work on two early episodes of the Fox hit sitcom, Family Guy and on the 1998 Disney/Pixar film A Bug's Life.

[23] After moving to Los Angeles, Rocco became a member of the Baháʼí Faith,[24] and he appeared in a number of productions related to the religion over the years.