Born in her mother's hometown of Warren, Ohio, Robin McKinley grew up an only child with a father in the United States Navy. She moved around frequently as a child and read copiously; she credits this background with the inspiration for her stories.

Her passion for reading was one of the most constant things in her childhood, so she began to remember events, places, and time periods by what books she read where. For example, she read Andrew Lang's Blue Fairy Book for the first time in California; The Chronicles of Narnia for the first time in New York; The Lord of the Rings for the first time in Japan; The Once and Future King for the first time in Maine. She still uses books to keep track of her life.

McKinley attended Gould Academy, a preparatory school in Bethel, Maine, and Dickinson College in 1970-1972. In 1975, she was graduated summa cum laude from Bowdoin College. In 1978, her first novel, Beauty, was accepted by the first publisher she sent it to, and she began her writing career, at age 26. At the time she was living in Brunswick, Maine. Since then she has lived in Boston, on a horse farm in Eastern Massachusetts, in New York City, in Blue Hill, Maine, and now in Hampshire, England, with her husband Peter Dickinson (also a writer, and with whom she co-wrote Water: Tales of Elemental Spirits in 2001) and two lurchers (crossbred sighthounds).

Over the years she has worked as an editor and transcriber (1972-73), research assistant (1976-77), bookstore clerk (1978), teacher and counselor (1978-79), editorial assistant (1979-81), barn manager (1981-82), free-lance editor (1982-85), and full-time writer. Other than writing and reading books, she divides her time mainly between walking her hellhounds, gardening, cooking, playing the piano, homeopathy, change ringing, and keeping her blog.