Herlihy joined the Navy in 1944. He attended Black Mountain College in North Carolina for two years, where he studied sculpture. He then moved to California and attended the Pasadena Playhouse College of the Theater.

Plays which he wrote include Streetlight Sonata (1950), Moon in Capricorn (1953), and Blue Denim (produced on Broadway in 1958).He directed Tallulah Bankhead in a touring production of his play Crazy October in 1959.Three of his one-act plays, collectively titled Stop You're Killing Me were presented by the Theater Company of Boston in 1969.

He wrote three novels: All Fall Down (1960), Midnight Cowboy (1960), and Season of the Witch (1971).His short stories were collected in The Sleep of Baby Filbertson and Other Stories (1959) and A Story That Ends in a Scream and Eight Others (1967), a collection which also included plays.

He acted in Edward Albee's play Zoo Story in 1963 in Boston and Paris.

He acted in the 1981 film Four Friends directed by Arthur Penn.

Herlihy committed suicide, aged 66, by taking an overdose of sleeping pills in Los Angeles.

Novels

• All Fall Down (1960)
• Midnight Cowboy (1965)
• The Season of the Witch (1971)

Plays

• Streetlight Sonata (1950)
• Moon in Capricorn (1953)
• Blue Denim (1958)
• Crazy October (1959)
• Stop, You’re Killing Me: Three Short Plays (1969)

Collections

• The Sleep of Baby Filbertson and Other Stories (1958)
• A Story That Ends with a Scream and Eight Others (1967)