Campion was born in Wellington, New Zealand, the second daughter of Edith (nee Beverley Georgette Hannah), an actress, writer, and heiress, and Richard M. Campion, a theatre and opera director. Her maternal great-grandfather was Robert Hannah, the shoe manufacturer of Antrim House. Her father was from a family of Exclusive Brethren. With her older sister, Anna, born a year and half before her, and brother, Michael, born seven years after, Campion grew up in the world of New Zealand theatre. Her parents founded the New Zealand Players theatre group. While initially rejecting the idea of a career in theatre or acting, she graduated with a bachelor's degree in Anthropology from Victoria University of Wellington in 1975. In 1976 Campion attended Chelsea Art School in London and travelled throughout Europe.
She graduated with a bachelor's degree in painting at the Sydney College of the Arts in Australia in 1979. Based on her education at Chelsea Art School and the Sydney College of the Arts Campion cites surrealist painter Frida Kahlo and sculptor Joseph Beuys as influences on her art. Dissatisfied with the limits of painting as a medium, Campion turned to film and created her first short film, Tissues in 1980. In 1981 she began studying at the Australian Film, Television and Radio School, where she made several more short films, and graduated in 1984.
Her first short film, Peel (1982) won the Short Film Palme d'Or at the 1986 Cannes Film Festival, and other awards followed for the shorts Passionless Moments (1983), A Girl's Own Story (1984) and After Hours (1984). Having left the Australian Film and Television School she directed an episode for ABC's light entertainment series Dancing Daze (1986), which led to her first TV film, Two Friends (1986) produced by Jan Chapman.
Sweetie (1989) was her feature debut, and won international awards. Further recognition followed with An Angel at My Table (1990), a biographical and psychological portrayal of the New Zealand poet Janet Frame. International recognition followed with another Palme d'Or at the 1993 Cannes Film Festival for The Piano, which won the best director award from the Australian Film Institute and an Academy Award for Best Original Screenplay in 1994. At the 66th Academy Awards, she was the second woman ever to be nominated for Best Director.
Campion's work since that time has tended to polarize opinion. The Portrait of a Lady (1996), based on the Henry James novel, featured Nicole Kidman, John Malkovich, Barbara Hershey and Martin Donovan. Holy Smoke! (1999) teamed Campion again with Harvey Keitel, this time with Kate Winslet as the female lead. In the Cut (2003), an erotic thriller based on Susanna Moore's bestseller, provided Meg Ryan an opportunity to depart from her more familiar onscreen persona. Her 2009 film Bright Star, a biographical drama about poet John Keats (played by Ben Whishaw) and his lover Fanny Brawne (Abbie Cornish), was shown at the Cannes Film Festival.
Campion was an executive producer for the 2006 documentary Abduction: The Megumi Yokota Story and has worked on the serial Top of the Lake. In a documentary about this BBC production she remarked that, 'creativity is like a visitor to a relaxed space inside you. It comes when you're not trying. It is insecure and shy. It needs love and acceptance. It needs non judgement. Let it be how it is ... Acting is about vulnerability. That's how you let the audience in.'
She has been announced as the as the head of the jury for the Cinéfondation and Short Film sections at the 2013 Cannes Film Festival.