Dorothy Coade Hewett was born and raised in Western Australia on an isolated farm in the wheat belt town of Wickepin. Until the age of twelve, she was educated by correspondence and had already begun writing short stories and poems. Between 1928 and 1938, Western Australia's Education Department conducted a program for correspondence pupils to develop poetry appreciation and writing skills. Pupils were sent illustrated 'Pattern Poetry' which they could follow to develop form and rhyming skills. Those who showed promise were then given special attention. Hewett's poem, 'Dreaming', written when she was nine years old, was published in an anthology of the children's work in 1938. Hewett later attended the University of Western Australia and at nineteen her poetry appeared in Meanjin. By the age of twenty-two she had won a drama competition and a national poetry competition.
In 1944 Hewett married Lloyd Davies and had one child. In 1948, after the failure of the marriage, she moved to Sydney where she lived and worked in factories in the poorer areas of of the city. For nine years she lived with Les Flood, boiler-maker and communist, with whom she had three sons. (One of those sons is the novelist Tom Flood.) Hewett had joined the Communist Party of Australia (CPA) when she was nineteen and was heavily involved in CPA activities in Sydney. (She resigned from the party in in 1968 following the Soviet invasion of Czechoslovakia.) Her novel Bobbin Up (1959), written in six weeks, was based on her own experience of working in a spinning mill, her membership of the CPA at that time, and her life in the inner city working class suburbs of Sydney.
When her relationship with Flood ended in 1960, Hewett returned to Perth, resumed studies at the University of Western Australia, completed her degree, taught English at the University of Western Australia and married Merv Lilley, merchant seaman and communist, with whom she had two daughters. (One of the daughters is the poet Kate Lilley.) After some years of tutoring at the university, Hewett again moved to Sydney and resumed writing. In her last years she and Merv Lilley moved to the Blue Mountains area of New South Wales.
Dorothy Hewett published collections of poetry, novels, an autobiography, and plays, as well as numerous articles and short stories. She was writer-in-residence at universities in Australia and the USA, she was awarded eight fellowships by the Literature Board of the Australia Council, and she had a lifetime Emeritus Fellowship from the Literature Board. Hewett was made a Member of the Order of Australia (AM) for services to literature.