Jocelyn Brando came to the stage naturally, first appearing in a theatrical production under the direction of her mother, who was a principal in an Omaha community theater group. Her mother, Dorothy Brando, had given Henry Fonda his start in theater in this same group. She made her Broadway debut soon after her 22nd birthday, appearing in The First Crocus at the Longacre Theatre on January 2, 1942; the play closed after five performances. Her next appearance on Broadway came two months after her younger brother began his role as Stanley Kowalski in Tennessee Williams' A Streetcar Named Desire.

Even before that, however, in the fall of 1947, both Jocelyn and Marlon would become two of the first fifty or so members of New York's newly formed Actors Studio, Jocelyn studying with Elia Kazan, Marlon with Robert Lewis.

On February 18, 1948, she appeared in her second role on Broadway. She played Navy nurse Lieutenant Ann Girard in Mister Roberts, which starred family friend Henry Fonda in the eponymous title role. The play was a smash hit, running about three years (1157 performances).

She did not complete the run of the play, appearing in the comedy The Golden State in the 1950-51 season, a flop that lasted but 25 performances, followed by a critically acclaimed, but commercially unsuccessful 1952 revival of Eugene O'Neill's Desire Under the Elms, which ran for only 46 performances. Brando would later appear in a Broadway revival of O'Neill's Mourning Becomes Electra.

It was her second film that was her best-known movie role: detective Glenn Ford's doomed wife in Fritz Lang's The Big Heat (1953). Her character is killed by a car bomb, intended for her husband. She also appeared in supporting roles in two of her brother's films, The Ugly American (1963) and The Chase (1965).

In the late 1960s, Jocelyn joined the cast of the CBS soap opera, Love of Life, where she created the role of Mrs. Krakauer, mother of Tess (Toni Bull Bua) and Mickey (Alan Feinstein). On primetime television, she played the recurring role of Mrs. Reeves on Dallas. Other television series that featured her work include Richard Diamond, Private Detective, Alfred Hitchcock Presents, Wagon Train, Riverboat, The Virginian, Kojak and Little House on the Prairie.

Many fans of the 1981 film Mommie Dearest believe Jocelyn portrayed Actress Barbara Bennett, sister to Constance Bennett and Joan Bennett, in the movie, but this is incorrect. It is merely coincidence that the Redbook Writer in the movie has the same name as the Actress.

Jocelyn Brando had two sons, Gahan Hanmer (by husband Don Hanmer) and Martin Asinof (by Writer Eliot Asinof). She died at her Santa Monica home, shortly after her 86th birthday, from undisclosed causes.