Stewart studied Journalism and English at Rhodes University, South Africa and worked as a journalist on the Argus in Cape Town. She came to Australia in 1977, working on the Illawarra Mercury in Wollongong and then at the Sun-Herald as a news and feature writer. She went freelance in 1985, and also began to write fiction. Her first book, Born Into the Country, the story of a black woman's struggles, was published in 1988 in South Africa.
She has had articles, reviews and essays published for a variety of publications including the Sydney Morning Herald, the Bulletin, GQ, Island Magazine, Harper's Bazaar and the Canberra Times.