[2] Harron's first stepmother, Virginia Leith, was discovered by Stanley Kubrick and acted in his first film, Fear and Desire and was also featured in the 1962 cult classic The Brain That Wouldn't Die.

Harron moved to England when she was thirteen and later attended St Anne's College, Oxford University, where she received a Bachelors in English.

[9][10] While in England, she dated Tony Blair, later the Prime Minister of the United Kingdom, and Chris Huhne, another Oxford student who later became a prominent politician.

After she had moved to London in her teen years she began attending the National Film Theatre where she was exposed to other international filmmakers like Fritz Lang, Howard Hawks, Claude Chabrol, and Roman Polanski.

[9] During the 1990s, Harron moved back to New York where she worked as a producer for PBS's Edge, a program dedicated to exploring American pop culture.

Harron suggested making a documentary about Solanas to her producers, who in turn encouraged her to develop the project into what would be her first feature film.

[17] Harron says she owes her success with her first film to Andy who helped to sell the controversial focus on the attempted murderess, Solanas.

[23] Harron's second film, American Psycho, released in 2000, is based on the book of the same title by Bret Easton Ellis, which is notorious for its graphic descriptions of torture and murder.

The New York Times' Stephen Holden wrote of the film: From the opening credits, in which drops of blood are confused with red berry sauce drizzled on an exquisitely arranged plate of nouvelle cuisine, the movie establishes its insidious balance of humor and aestheticized gore.

[30] Harron has a liking for darker and more controversial topics, such as Valerie Solanas, but it was the satirical nature of the book that "inspired her film about perfunctory violence and obsessive consumption.

"[31] As Harron began production, the crew had to contend with threats of protest, as the issue of violence in the media became crystallized by the Columbine shootings.

[8] Although some criticized American Psycho for its violence against women, Harron and Turner made conscious decisions that project the female influence on this adaption.

The film shows Page as the daughter of religious and conservative parents, as well as the fetish symbol who became a target of a Senate investigation of pornography.

Harron has described the film as a "gothic coming-of-age story"[36] that explores the nuanced friendships of teenage girls as they are repeatedly confronted with the prospect of adulthood.

Harron directed the 2018 independent film Charlie Says, with a screenplay by Turner, which tells the real-life story of how three of Charles Manson's female followers (Susan Atkins, Patricia Krenwinkel, and Leslie Van Houten) came to terms with the magnitude of their crimes while incarcerated in the 1970s.

Harron stated that she was fascinated by the psychological aspects of how the women ended up committing murder as a result of both manipulation by Manson and feelings of solidarity with one another.

[39][40] In addition to her films, Harron was also the executive producer of The Weather Underground, a documentary looking at the Weathermen (political activists and extremists of the 1970s).

Working on the episode of Six Feet Under "The Rainbow of Her Reasons", Harron was brought back together with I Shot Andy Warhol actress, Lili Taylor.

"[35] Although her films deal with controversial materials, like American Psycho, in the opinion of director Buffy Childerhose, she does not put emphasis on gore and violence.