He was born Charles Farrell Myers in California, and grew up in Coalinga. Later taking the pseudonym Henry Farrell, his first novel was The Hostage, which was published in 1959.

With Lukas Heller, Farrell co-wrote the screenplay for Hush... Hush, Sweet Charlotte (1964), starring Davis and Olivia de Havilland. It was based on a story he wrote entitled Whatever Happened to Cousin Charlotte?, and the script earned Heller and Farrell a 1965 Edgar Award, from the Mystery Writers of America, for Best Motion Picture Screenplay. He wrote the original screenplay for What's the Matter with Helen? (1971), which starred Debbie Reynolds and Shelley Winters.

His wife was actress Molly Dodd, who died in 1981. Dodd appeared in small roles in two movies written by Farrell, the TV production How Awful About Allan starring Anthony Perkins and Julie Harris and What's the Matter with Helen?

French director François Truffaut's 1972 movie Une belle fille comme moi was based on Farrell's 1967 novel Such a Gorgeous Kid Like Me.

In 2002, Farrell tried his hand at writing the book for a stage play, the musical version of What Ever Happened to Baby Jane? The world premiere of the show was on October 9 in Houston, Texas, with Millicent Martin in the title role and Leslie Denniston as Blanche.

Henry Farrell died in his Pacific Palisades, California, home at age 85. According to his obituary, he completed another novel, titled A Piece of Clarisse, shortly before his death[1]. There is currently no word on publication.