Mavis Thorpe Clark was born in Melbourne and educated at the Methodist Ladies College. Her writing career began at the age of fourteen, when the Australasian published, as a children's serial, her work The Red School. Her first published book, written when she was 18 and sold to Whitcombe and Tombs in 1930 for the then considerable sum of £30, was Hatherley's First Fifteen, a boy's adventure story about Rugby football.
Following this first publication, Clark wrote more newspaper serials, short stories and radio scripts, and saw several novels published as books in the early 1950s. She began writing for children in the late 1950s, attracting wide admiration for The Brown Land Was Green (1956). She was nominated for more awards during the 1960s and won the Book of the Year Award of the Children's Book Council of Australia for The Min Min (1966).
Clark published more than two dozen books for children, several novels for adults and a history of the War Widows' Guild of Australia. Clark also wrote non-fiction series for children including Life in Australia Series and Early Australians Series (London, 1930). She used the pseudonym 'Thorpe Clark' for submissions to Cole's anthologies.