Julia Cameron was born and raised in a Chicago suburb, and grew up Catholic. She started college at Georgetown University, then transferred to Fordham. She started her journalism career at the Washington Post, then moved on to Rolling Stone.

She met Martin Scorsese when interviewing him for Rolling Stone. They married in 1975 and divorced in 1977; Cameron was Scorsese's second wife. They have one daughter, Domenica Cameron-Scorsese, born in 1976. Cameron and Scorsese collaborated on three films. Cameron's film, God's Will, is based on the Cameron-Scorsese marriage and divorce, portraying a divorced, self-centered show business couple who die unexpectedly and end up fighting in heaven over what will happen to their daughter.

A review of Cameron's memoir Floor Sample states that Cameron "reveals the dark side of her privileged life: her descent into alcoholic blackouts and drug-induced paranoia as well as descriptions of her bouts with psychosis." In 1978, reaching a point in her life when writing and drinking could no longer coexist, Cameron stopped the drugs and alcohol, and began teaching creative unblocking, which propelled her to fame after she published the book based on her teachings, The Artist's Way. She states creativity is an authentic spiritual path.

Cameron has taught filmmaking, creative unblocking, and writing. She has taught at The Smithsonian, Esalen, the Omega Institute, and the New York Open Center. At Northwestern University, she was writer in residence for film. In 2008 she taught a class at the New York Open Center, "The Right to Write," named and modeled after one of her bestselling books, which reveals the importance of writing.

Cameron has lived in Los Angeles, Chicago, Taos, and Washington D.C.,