Margaret Stiller was born in Adelaide, but moved to the Barossa at the age of nine. She trained as a teacher and as a librarian. In 1953 she married Wilfried Stiller and went to live in Alice Springs, where he was teaching. She spent five years in Alice Springs, teaching on the School of the Air from 1956 to 1958 when she had to retire due to ill health. They moved to Darwin where she became an advisory teacher-librarian, travelling around the Northen Territory helping schools set up worthwhile school libraries. During the 1970s she published several works on children's books and books for school libraries. In 1982 she was awarded the MBE for services to education and to the community. .
In 1984 she was invalided out of her job with chronic fatigue syndrome, and advised to leave the tropics. She and her husband moved to Adelaide. Although still handicapped by chronic fatigue, she wrote four historical romances after retiring and also published The Joy of Children's Books (1989) and 'Help Lord! No-one's Borrowing any Books': Creative Church Librarianship (1994). She founded and was the Executive Officer of the Australian Church Library Association (ACLA). She travelled around Australia training church librarians, and put out a quarterly magazine called Off the Shelf.
ACLA established the Margaret Stiller Memorial Lecture in her memory.