Norton was the daughter of a physician, and was raised in a Georgian house at the end of the High Street in Leighton Buzzard. The house now consists of part of Leighton Middle School, known within the school as The Old House, and was reportedly the setting of her novel The Borrowers. She married Robert C. Norton in 1927 and had four children, 2 boys and 2 girls. Her second husband was Lionel Boncey, who she married in 1970. She began working for the War Office in 1940 before the family moved temporarily to the United States.

She began writing while working for the British Purchasing Commission in New York during the Second World War. Her first book was The Magic Bed Knob; or, How to Become a Witch in Ten Easy Lessons published in 1943, which, together with the sequel Bonfires and Broomsticks, became the basis for the Disney film Bedknobs and Broomsticks.

Mary Norton died of a stroke in Devon, England in 1992.

The Borrowers series

There have been several screen adaptations of The Borrowers:

• The Borrowers: a 1973 American made-for-TV movie.
• The Borrowers: a 1992 BBC TV series and its 1993 sequel The Return of the Borrowers, both starring Ian Holm and Penelope Wilton.
• The Borrowers: a 1997 film with a British/American cast including Tom Felton, John Goodman, Jim Broadbent, Celia Imrie and Mark Williams.
• The Borrower Arrietty: a 2010 Japanese animated film from Studio Ghibli.