Joan Delano Aiken was born on September 4, 1924, in Rye, England. Her father, Conrad Aiken, was a famous poet, and she knew from an early age that she also wanted to write for a living. While still a student, she had two of her poems published.

In the 1940s Aiken wrote radio scripts for the British Broadcasting Corporation and served as a librarian for the United Nations Information Office in London. When her first husband, journalist Ron Brown, died in 1955, Aiken worked as an editor for the short story magazine Argosy to support herself and her two children. She also contributed short stories to various publications. These stories were later collected to form her first two publications: All You've Ever Wanted, published in 1953, and More Than You Bargained For (1955).

Aiken is known for creating a type of book called the “unhistorical romance.” The books combine humor and action with traditional elements found in myths and fairy tales. The stories are set in a made-up historical time period. The Wolves of Willoughby Chase (1962), Black Hearts in Battersea (1964), Nightbirds on Nantucket (1966), The Whispering Mountain (1968), Dido and Pa (1986), and Is Underground (1993) are all examples of unhistorical romances. Although these books were written mainly for children, they appeal to many adults as well.

Aiken's other children's books include The Skin Spinners (1976), The Shadow Guests (1980), A Whisper in the Night (1982), Up the Chimney Down (1984), Past Eight O'Clock (1986), Give Yourself a Fright (1989), and A Fit of Shivers: Tales for Late at Night (1990). Arabel's Raven (1972) was the first of several funny books she wrote about a preschooler and her pet raven.

In 1972 the Mystery Writers of America honored Aiken's Night Fall (1969) with the Edgar Allan Poe Award for best juvenile mystery. In 1974 The New York Times selected Midnight Is a Place as one of the year's outstanding books. For her services to children's literature, Aiken was named Member of the Order of the British Empire in 1999. She died on Jan. 4, 2004, in Petworth, West Sussex, England.