St John was born in 1941 in a suburb of Sydney. She wrote four novels in her short writing life. She was 52 when the first, The Women in Black, was published in 1993. The other three followed soon after, and form a loose trilogy set in contemporary London, Notting Hill, where she lived most of her adult life, particularly favoured. The Essence of the Thing was shortlisted for the Booker Prize.
Madeleine St John died in London in June 2006.