Formerly a staff journalist on The Sydney Morning Herald, The Australian and Vogue Australia and a documentarian, Helen O'Neill has published a wide range of works, primarily biographical: she has won awards for her journalism and travel writing, and her biographies (including Daffodil: Biography of a Flower) have been shortlisted for such awards as The Nib, the National Biography Award, the ABIA Biography of the Year, and the Age Book of the Year. Her biography of Florence Broadhurst was longlisted for a Walkley Award.
In 2018, she was serving as a director on the boards of both the Australian Society of Authors and Copyright Agency.