De Niro was born in New York City, the son of Robert De Niro, Sr., an abstract expressionist painter, sculptor, and poet of Irish and Italian descent (De Niro's great-grandparents were Italian immigrants from the village of Ferrazzano, Molise), and Virginia Admiral, also a painter. They had met at the painting classes of Hans Hofmann in Provincetown, Massachusetts. His parents divorced when he was two years old. A biographer, John Baxter, claims that his father was homosexual, and had relationships with poet Robert Duncan, playwright Tennessee Williams, and artist Jackson Pollock. De Niro first attended the Little Red School House School and was then enrolled by his mother at the High School of Music and Art in New York. He dropped out at the age of 13 and joined a Little Italy street gang, where he earned the nickname Bobby Milk due to his white complexion. He then had a falling-out with his father, although they were eventually reconciled when, aged 18, he flew out to Paris to bring his father home when he had been suffering from depression. De Niro attended the Stella Adler Conservatory, as well as Lee Strasberg's Actor's Studio (although De Niro conflicted with Strasberg's methods, and used his membership there mostly as a professional advantage). At the age of 16 he toured in Chekhov's The Bear.

At the age of 20 came his first important collaboration with Brian De Palma in 1963 when he appeared in The Wedding Party; it was not released until 1969, however. He spent much of the 1960s working in theatre workshops and off-Broadway productions. He was an extra in the French film Three Rooms in Manhattan, (1965) and was reunited with De Palma in Greetings, 1968 and Hi, Mom, 1970. He gained popular attention with his role as a sick Baseball catcher in Bang the Drum Slowly (1973). The same year he began his fruitful collaboration with Scorsese when he played his memorable role as the small time Mafia hood "Johnny Boy" alongside Harvey Keitel's "Charlie" in Mean Streets. This led to an incredibly successful relationship between the actor and director in films such as Taxi Driver (1976), New York, New York (1977), Raging Bull (1980), The King of Comedy (1983), Goodfellas (1990), Cape Fear (1991) and Casino (1995). In these films, De Niro has primarily played charming sociopaths. Taxi Driver is particularly important to De Niro's career; his iconic performance as Travis Bickle shot him to stardom and forever linked De Niro's name with Bickle's famous "you talkin' to me?" monologue. In 1978, De Niro played "Michael Vronsky" in the acclaimed Vietnam War film Deer Hunter. Another notable role was in Sergio Leone's Once Upon a Time in America as the Jewish gangster "David 'Noodles' Aaronson" (1984). Beginning in the mid-1980s, De Niro began expanding into occasional comedic roles, and has had much success in that area as well with such films as Brazil (1985), Midnight Run (1988), Wag the Dog (1997), Analyze This (1999), Analyze That (2002), Meet the Parents (2000) and Meet the Fockers (2004). In the late 1980s, De Niro began to invest in the Tribeca area of New York, including establishing a film studio and a film festival in the area. De Niro later admitted that some of the 'below par' film roles he had taken in the 1990s were solely for the purpose of supporting these charitable ventures. He has won two Academy Awards: as Best Actor for his role in Raging Bull; and as Best Supporting Actor for The Godfather, Part II. Interestingly, De Niro and Marlon Brando are the only pair of actors who have won Academy Awards for portraying the same character: Brando won for playing the elderly Don Vito Corleone (although he declined the award) in The Godfather while De Niro later won the award for playing the young Vito in The Godfather, Part II. Brando and De Niro did not work together on screen until The Score (2001). De Niro actually auditioned for the role of Sonny in the first Godfather but the role was given to James Caan. When director Francis Ford Coppola was in pre production for The Godfather, Part II he remembered De Niro's audition, and knew he was going to play young Vito Corleone. Praised for his commitment to roles, De Niro gained 60 pounds (27 kg) and learned how to box for his portrayal of Jake LaMotta in Raging Bull, ground his teeth for Cape Fear, and learned to play the saxophone for New York, New York. De Niro is considered a skilled observer of physical tics and details, and is an intense perfectionist. He is often compared to fellow acting icon Al Pacino with whom he appeared in The Godfather, Part II in 1974 and Heat in 1995. His next project will see the versatile actor handling both sides of the camera in The Good Shepherd (2006), which DeNiro is directing and co-starring alongside Matt Damon and Angelina Jolie. The movie also marks the return of actor Joe Pesci, who has been offscreen for almost a decade, in a small role. The film is expected to be a heavy Oscar contender for 2006.