Annette Macarthur-Onslow studied art at East Sydney Technical College, freelanced as a commercial artist and spent time working with a marionette programme which was produced for television. Relocating to England, Macarthur-Onslow attended the National Art School (London) and worked as a production assistant for a London publisher.
She wrote and illustrated several publications, and the first of her three children's books, Uhu
(1969), won the 1970 Book of the Year Award of the Children's Book Council. In 1971 Macarthur-Onslow was selected by the Children's Section of the Library Association of Australia to represent Australia at the 1971 Biennale d'Illustrations Bratislava, the first time that an Australian had exhibited at the Biennale; she was awarded a Diplome d'Honneur for her exhibited work from Uhu and Minnie
(1971). Macarthur-Onslow published the semi-autobiographical Round House
(based on the author's notes, 'diary jottings and sketches'), in 1975; this account details the period she spent living in the woodland cottage in Gloucestershire which provided the setting for her earlier works, Uhu and Minnie.
Working extensively as a freelance illustrator both in Australia and overseas, Macarthur-Onslow has illustrated the texts of many authors, including Judith Wright, Hesba Brinsmead and Elyne Mitchell (qq.v.).