She made her screen debut as an Actress in 1956 in The Mountain (1956) for Paramount with Spencer Tracy and Robert Wagner. Using the stage name Anna Kashfi, the twenty-two-year-old played a Hindu girl. In her next film a year later, Battle Hymn (1957), she co-starred with Rock Hudson as a Korean girl. A year after that she played a Mexican in Cowboy (1958) with Glenn Ford and Jack Lemmon. Her next and last film during this period was Night of the Quarter Moon (1959), where she played the African American wife of singer Nat King Cole. She made a few appearances on television, including the series Adventures in Paradise, though drug and alcohol problems reportedly contributed to the premature end of her acting career.
Kashfi married Marlon Brando, whom she had met in the summer of 1956, on 11 October 1957. They divorced a year and a half later on 22 April 1959.
They had a son, Christian Devi Brando (1958–2008), whom she called "Devi". Kashfi and Marlon fought bitterly over Christian, with Marlon eventually winning custody. In the 1990s, Christian was tried for killing his half-sister Cheyenne's boyfriend. Jailed for the crime, he later died of pneumonia in Los Angeles in 2008, aged 49. Kashfi married James Hannaford, a salesman, in 1974. Kashfi had one grandson, Michael Brando (born 1988).
The matter of Kashfi's ethnic heritage has remained in question. Both her English-born parents maintained she was their biological daughter, born, her Father told Parade magazine in 1959, "to my wife in 1934 when I was employed by the Bengal-Nagupur railway as a station master". Parade stated that its investigation determined that "her baptismal certificate bears this out" and furthermore stated that she had a brother, Bosco Brian Patrick O'Callaghan, who was then attending a technical college in Cardiff.
In her 1979 book, Brando for Breakfast, Kashfi retreated halfway and claimed she is half-Indian, maintaining that rather than william O'Callaghan being her real Father he was in effect her stepfather. She stated her biological Father was Indian and she was the result of an "unregistered alliance" between him and her mother. When questioned earlier in life about her daughter's heritage, her mother had told the press "There is no Indian blood in my family or my husband's family", which indeed rules out her ancestry and O'Callaghan's, but does admit the logical possibility of Anna's Father having been Indian. Film Director Edward Dmytryk, who directed the Actress in her first film, stated in a New York Times interview (entitled "Kashfi Called Welsh") the day before her wedding to Brando that he knew her real surname was Irish but assumed that she was half-Indian.