Radley Henry Metzger was born on January 21, 1929 on the Grand Concourse in The Bronx, New York City, and was the second son of Jewish parents, Julius and Anne. He claimed he found relief from his allergies in movie theaters, especially at the Audubon Ballroom theatre, while growing up. Later, Metzger received a B.A. in Dramatic Arts from City College of New York, where he studied with filmmakers Hans Richter and Leo Seltzer. He also studied acting privately with Director Harold Clurman. During the Korean War, Metzger served in the U. S. Air Force with the 1350th Photographic Group, which interrupted his graduate studies at Columbia University. His older brother, now deceased, had become a physician. Metzger later married and had a daughter.

Early in his career, in the 1950s, Metzger worked primarily as a film Editor and was a member of Local 771 of the IATSE. He was employed in editing trailers for Janus Films (now The Criterion Collection) a major distributor of foreign art films, especially those of Michelangelo Antonioni, Ingmar Bergman, Federico Fellini, Jean-Luc Godard and François Truffaut. In 1953, Metzger was credited as assistant Director to william Kyriakis on the film Guerilla Girl. Later, in 1956, he worked on the dubbing of And God Created Woman, starring Brigitte Bardot. His directorial film debut, Dark Odyssey (1961) (co-directed with Kyriakis), was a drama concerning the experiences of a Greek immigrant arriving in New York. The film was favorably reviewed by The New York Times and others. In 1959, he edited the film The Gangster Story, starring Walter Matthau, and, in 1960, Metzger was a presenter for the Japanese film, The Warped Ones.

Later, in 1961, along with film distributor Ava Leighton, Metzger founded Audubon Films. The company was named after the Audubon Ballroom theatre, one of his favorite movie theaters while growing up. The newly founded distribution company specialized in importing international features, some of which were marketed into the gradually expanding adult erotic film genre. Metzger's skills as an Editor were employed in re-cutting and augmenting many of the features Audubon handled, including The Twilight Girls (FR,1957) and, their first runaway success, Mac Ahlberg's I, a Woman (DN/SW,1965).

Metzger's second directorial effort, The Dirty Girls (shot in 1963 and released in 1965), marked his emergence as a major auteur in the adult erotic film genre. His subsequent films were often shot in Europe and adapted from novels or other literary sources, including Carmen (by Prosper Mérimée), La Dame aux Camélias (by Alex Andre Dumas), L'image (by Catherine Robbe-Grillet), Naked Came the Stranger (by Penelope Ashe), Pygmalion (by George Bernard Shaw), Six Characters in Search of an Author (by Luigi Pirandello), The Cat and the Canary (by John Willard), and Thérèse et Isabelle (by Violette Leduc). He cites John Farrow, Claude Lelouch, Michael Powell, Alain Resnais and Orson Welles as influencing his work. Metzger worked with the French film Director Jean Renoir, as well as the American actor Hal Linden. Andy Warhol, who helped begin the Golden Age of Porn with his 1969 film Blue Movie, was a fan of Metzger's film work and commented that Metzger's 1970 film, The Lickerish Quartet, was “an outrageously kinky masterpiece”. In 1972, Metzger directed the film Score, based on an erotic off-Broadway play that included Sylvester Stallone. Films directed by Metzger included musical scores composed by Georges Auric, Stelvio Cipriani, Georges Delerue, and Piero Piccioni. Metzger's signature film style of his "elegant erotica" had developed into being "a Euro-centric combination of stylish decadence, wealth and the aristocratic".

Under the pseudonym "Henry Paris," Metzger also directed several explicit adult erotic features during the mid- to late-1970s. These films were released during the Golden Age of Porn (inaugurated by the 1969 release of Andy Warhol's Blue Movie) in the United States, at a time of "porno chic", in which adult erotic films were just beginning to be widely released, publicly discussed by celebrities (like Johnny Carson and Bob Hope) and taken seriously by film critics (like Roger Ebert). Metzger's films are typified by high production values, especially The Private Afternoons of Pamela Mann (1975) and The Opening of Misty Beethoven (1976), and are generally critically celebrated. Some historians assess The Opening of Misty Beethoven, based on the play Pygmalion by George Bernard Shaw (and its derivative, My Fair Lady), as attaining a mainstream level in storyline and sets and is considered, by award-winning author Toni Bentley, the "crown jewel" of the Golden Age of Porn.

Some of the adult erotic "Henry Paris" films, including Score (1974), have also been presented in softcore versions. Many of Metzger's films, including Score (1974), The Image (1975), The Opening of Misty Beethoven (1976) and Barbara Broadcast (1977), as well as his earlier softcore films, Camille 2000 (1969) and The Lickerish Quartet (1970), have been released in Blu-ray versions.

In 1977, Metzger's film The Opening of Misty Beethoven was the recipient of the first Adult Film Association of America awards for Best Direction (as Henry Paris), Best Film, and Best Actor (Jamie Gillis) and, as well, won the X-Caliber award for Best Direction (as Henry Paris).

With his 1978 feature The Cat and the Canary, Metzger distinguished himself as one of the few adult film auteurs to direct a dramatic feature outside of the adult erotic film genre. The film starred Honor Blackman, Edward Fox, Dame Wendy Hiller and Carol Lynley.

In the 1990s, as a result of the passing of his long-time partner, Ava Leighton, due to cancer, Metzger produced several videos on alternative health care, including one on cancer treatment and a five-part video series on homeopathy with Dr. Andre Weil. According to Metzger: "I felt that in the 1990s, people needed more information on an intelligent approach to health and disease — that they needed to know about alleviating guilt. That was my emphasis."

In 2001, Metzger's film work was the subject of a retrospective in Boston, Massachusetts.

In 2002, Metzger's film The Opening of Misty Beethoven won Best Classic Release on DVD by the Adult Film Association of America.

In 2010, Metzger was also the recipient of a Lifetime Achievement Award from the Oldenburg International Film Festival, where he served as a judge in 2011.

In 2011, Metzger's film work was the subject of a retrospective at the UCLA Film and Television Archive.

In 2014, Metzger's film work was the subject of a retrospective at the Film Society of Lincoln Center.

Radley Metzger died of undisclosed causes in New York City on Friday, March 31, 2017 at the age of 88.