Margaret Balderson was born in Sydney. She attended Fort Street Girls High School and, after leaving, worked as a public librarian for ten years.
During the 1960s, she worked in Norway for two years, a residence that inspired her first novel, When Jays Fly to Barbmo (1968). On her return to Australia, she resumed library work in Sydney, then was the resident house-mistress and librarian at Frensham School, Mittagong, NSW. It was at Frensham that she began to write When Jays Fly to Barbmo.
Set in Norway, this story of a young girl growing up is an early example of the adolescent novel in Australia. The novel was well received, winning the Book of the Year Award of the Children's Book Council of Australia. Her next book, A Dog Called George (1975), is for younger readers. The story of an introverted boy released from shyness by an Old English sheepdog, A Dog Called George was nominated for several awards. After writing the picture book Blue and Gold Day (1979), Balderson maintained a long silence. But, after collaborating with several co-volunteers from a dingo sanctuary, she completed Sea Bird (2002), a story inspired by several key words provided by each contributor.