Walken's films have grossed more than $1.8 billion in the United States. He has also played the main role in the Shakespeare plays Hamlet, Macbeth, Romeo and Juliet, and Coriolanus. He has several times guest-hosted Saturday Night Live, his most notable role being Bruce Dickinson in the "More Cowbell" sketch.

Walken debuted as a film director and script writer with the short (five-minute) film "Popcorn Shrimp" in 2001. He also wrote and acted the main role in a play about Elvis Presley titled Him in 1995.

Named after actor Ronald Colman, Walken was born Ronald Walken in Astoria, Queens, New York, into a Methodist family. His mother, Rosalie (née Russell; 1907–2010), was a Scottish immigrant from Glasgow, and his father, Paul Walken (1903–2001), emigrated from Germany in 1928 with his brothers, Wilhelm and Alois. His father owned and operated "Walken's Bakery" in Astoria.

Influenced by their mother's own dreams of stardom, he and his brothers Kenneth and Glenn were child actors on television in the 1950s. Walken studied at Hofstra University on Long Island, but did not graduate. Walken initially trained as a dancer in music theatre at the Washington Dance Studio before moving on to dramatic roles in theatre and then film.

Walken first appeared on the screen as an extra in numerous anthology series and variety shows during the Golden Age of Television. After appearing in a sketch with Martin and Lewis on The Colgate Comedy Hour, Walken decided to become an actor. He landed a regular role in the 1953 television show The Wonderful John Acton as the show's narrator. During this time, he was credited as "Ronnie Walken".

Over the next two years, he appeared frequently on television (landing a role in the experimental film Me and My Brother) and had a thriving career in theatre. In 1964, he changed his first name to "Christopher" at the suggestion of a friend who believed the name suited him better. Coincidentally, Walken's last credited role under the name "Ronnie" was a character with the name of "Chris". Nowadays, he prefers to be known informally as "Chris" instead of "Christopher".

Walken made his feature film debut with a small role opposite Sean Connery in Sidney Lumet's The Anderson Tapes . In 1972's The Mind Snatchers A.K.A. The Happiness Cage, Walken played his first starring role. In this science fiction film, which deals with mind control and normalization, he plays a sociopathic U.S. soldier stationed in Germany.

Paul Mazursky's 1976 film Next Stop, Greenwich Village has Walken under the name "Chris Walken" playing fictional poet and ladies man Robert Fulmer. Woody Allen's 1977 film Annie Hall has Walken playing the suicidal brother of Annie Hall (Diane Keaton). In 1978, he appeared in Shoot the Sun Down, a western filmed in 1976 that costarred Margot Kidder. Along with Nick Nolte, Walken was considered by George Lucas for the part of Han Solo in Star Wars; the part ultimately went to Harrison Ford.

Walken won an Academy Award for Best Supporting Actor in Michael Cimino's 1978 film The Deer Hunter. He plays a young Pennsylvania steelworker who is emotionally destroyed by the Vietnam War. To help achieve his character's gaunt appearance before the third act, Walken consumed only bananas, water, and rice for a week.

Walken's first film of the 1980s was the controversial Heaven's Gate, helmed by Deer Hunter director Cimino. Walken also starred in the 1981 action adventure The Dogs of War, directed by John Irvin. In 1982, he played a socially awkward, but gifted theater actor in "Who Am I This Time?" He surprised many critics and filmgoers with his intricate tap-dancing striptease in Herbert Ross's musical Pennies From Heaven. Walken then played schoolteacher-turned-psychic Johnny Smith in David Cronenberg's 1983 adaptation of Stephen King's The Dead Zone. That same year, Walken also starred in Brainstorm alongside Natalie Wood and (in a minor role) his wife, Georgianne.