Born Marian Searle, she was educated at McMaster University and McGill University, where she wrote her Masters thesis on the English Canadian novel, under the supervision of Hugh MacLennan. She taught briefly at McGill and at the University of Montana. She married Howard Engel in 1962, and began to raise a family and pursue a writing career. Her first published novel, No Clouds of Glory, was published in 1968.
Engel's most famous and controversial novel was Bear (1976), a tale of erotic love between a librarian and a bear which won the Governor-General's Award that year. She also wrote a number of children's books.
Her other works included: The Honeyman Festival (1970), Monodromos (1974), Easter Egg (1975), The Glassy Sea (1979), Lunatic Villas (1981), The Tattooed Woman (1985), Joanne, The Year of the Child and Sunbeams from a Golden Machine.
After Engel's death in 1985, the Writer's Development Trust of Canada instituted the Marian Engel Award, which is presented annually to a woman writer in mid-career.