Cassavetes played bit-parts in B pictures and in television serials, until gaining notoriety in 1955 as a vicious killer in The Night Holds Terror, and as a juvenile delinquent in the live TV drama Crime in the Streets.
Cassavetes would repeat this performance in the 1956 film version.
His first starring role in a feature film was Edge of the City (1957), which co-starred Sidney Poitier.
He was briefly under contract to Metro-Goldwyn-Mayer and co-starred with Robert Taylor in the western Saddle the Wind, written by Rod Serling.
In the late 1950s, Cassavetes guest-starred in Beverly Garland's groundbreaking crime drama, Decoy, about a New York City woman police undercover detective.
Thereafter, he played Johnny Staccato, the title character in a television series about a jazz pianist who also worked as a private detective.
In total he directed five episodes of the series, which also features a guest appearance by his wife Gena Rowlands.
It was broadcast on NBC between September 1959 and March 1960 when it was acquired by ABC and although critically acclaimed, the series was cancelled in September 1960.
Cassavetes would appear on the NBC interview program, Here's Hollywood.

In 1961 Cassavetes signed a seven-year deal with Paramount.
Cassavetes directed two movies for Hollywood in the early 1960s – Too Late Blues (1961) and A Child Is Waiting.
A Child Is Waiting (1963) starred Burt Lancaster and Judy Garland.
He also starred in the CBS western series Rawhide, in the episode "Incident Near Gloomy River" (1961).
In the 1963–1964 season he was cast in the ABC medical drama about psychiatry, Breaking Point.
In 1964, he again co-starred with his wife, this time in an episode of The Alfred Hitchcock Hour anthology program, and in 1965, he appeared on ABC's western series, The Legend of Jesse James.
The same year he also guest-starred in the World War II series, Combat!,
in the episode "S.I.W." as well as insane nuclear scientist Everett Lang in Voyage to the Bottom of the Sea, season 2, episode "The Peacemaker".

With payment for his work on television, as well as a handful of film acting jobs, he was able to relocate to California and to make his subsequent films independent of any studio, as Shadows had been made.
The films in which he acted with this intention include Don Siegel's The Killers (1964), the motorcycle gang movie Devil's Angels (1967), The Dirty Dozen (1967), for which he was nominated for an Academy Award for Best Supporting Actor, Roman Polanski's Rosemary's Baby (1968), and The Fury (1978).
Cassavetes portrayed the murderer in a 1972 episode of the TV crime series Columbo, titled "Étude in Black".
Cassavetes and series star Peter Falk had previously starred together in the 1969 mob action thriller Machine Gun McCain.
Cassavetes played bit-parts in B pictures and in television serials, until gaining notoriety in 1955 as a vicious killer in The Night Holds Terror, and as a juvenile delinquent in the live TV drama Crime in the Streets. Cassavetes would repeat this performance in the 1956 film version. His first starring role in a feature film was Edge of the City (1957), which co-starred Sidney Poitier. He was briefly under contract to Metro-Goldwyn-Mayer and co-starred with Robert Taylor in the western Saddle the Wind, written by Rod Serling. In the late 1950s, Cassavetes guest-starred in Beverly Garland's groundbreaking crime drama, Decoy, about a New York City woman police undercover detective. Thereafter, he played Johnny Staccato, the title character in a television series about a jazz pianist who also worked as a private detective. In total he directed five episodes of the series, which also features a guest appearance by his wife Gena Rowlands. It was broadcast on NBC between September 1959 and March 1960 when it was acquired by ABC and although critically acclaimed, the series was cancelled in September 1960. Cassavetes would appear on the NBC interview program, Here's Hollywood.
In 1961 Cassavetes signed a seven-year deal with Paramount. Cassavetes directed two movies for Hollywood in the early 1960s – Too Late Blues (1961) and A Child Is Waiting. A Child Is Waiting (1963) starred Burt Lancaster and Judy Garland. He also starred in the CBS western series Rawhide, in the episode "Incident Near Gloomy River" (1961). In the 1963–1964 season he was cast in the ABC medical drama about psychiatry, Breaking Point. In 1964, he again co-starred with his wife, this time in an episode of The Alfred Hitchcock Hour anthology program, and in 1965, he appeared on ABC's western series, The Legend of Jesse James. The same year he also guest-starred in the World War II series, Combat!, in the episode "S.I.W." as well as insane nuclear scientist Everett Lang in Voyage to the Bottom of the Sea, season 2, episode "The Peacemaker".
With payment for his work on television, as well as a handful of film acting jobs, he was able to relocate to California and to make his subsequent films independent of any studio, as Shadows had been made. The films in which he acted with this intention include Don Siegel's The Killers (1964), the motorcycle gang movie Devil's Angels (1967), The Dirty Dozen (1967), for which he was nominated for an Academy Award for Best Supporting Actor, Roman Polanski's Rosemary's Baby (1968), and The Fury (1978). Cassavetes portrayed the murderer in a 1972 episode of the TV crime series Columbo, titled "Étude in Black". Cassavetes and series star Peter Falk had previously starred together in the 1969 mob action thriller Machine Gun McCain.
John Cassavetes