Margery Sharp was born Clara Margery Melita Sharp in 1905 in Wiltshire. She spent some of her childhood in Malta, and on the family's return to England became a pupil at Streatham Hill High School.
She later studied at Bedford College, London, where she claimed her time was devoted 'almost entirely to journalism and campus activities.'
Still living in London, she began her writing career at the age of twenty-one, becoming a contributor of fiction and non-fiction to many of the most notable periodicals of the time in both Britain and America.
In 1938 she married Major Geoffrey Castle, an aeronautical engineer. On the outbreak of World War II, she served as a busy Army Education Lecturer, but continued her own writing both during and long after the conflict. Many of her stories for adults became the basis for Hollywood movie screenplays, in addition to the 'Miss Bianca' children's series, animated by Disney as The Rescuers in 1977.
Margery Sharp ultimately wrote 22 novels for adults (not 26, as is sometimes reported), as well as numerous stories and novellas (many of them published only in periodicals) and various works for children. She died in Suffolk in 1991, one year after her husband.