[1] He began his career as a journalist for Time magazine before expanding into writing criticism, essays, novels, and screenplays.

He was the son of Dorothy Frances (née Burns) and Richard Edwin Dunne (1894–1946), a hospital chief of staff and heart surgeon.

John's maternal grandfather, Dominick Francis Burns (1857–1940), founded the Park Street Trust Company.

"[8] He invited her to travel to Connecticut one weekend in 1963 to visit his family, New England Irish Catholic, with six children.

Critically acclaimed bestselling books followed for each, including Dunne's The Studio, his nonfiction account of 20th Century Fox.

[2][4] They also collaborated on a series of screenplays, including The Panic in Needle Park (1971), A Star Is Born (1976), and True Confessions (1981), an adaptation of Dunne's novel of the same name.

[2][4] He wrote several novels, among them True Confessions, based loosely on the Black Dahlia murder, and Dutch Shea, Jr.

He was the writer and narrator of the 1990 PBS documentary L.A. is It with John Gregory Dunne, in which he guided viewers through Los Angeles's cultural landscape.