Osborne's writing career began "one day, out of the blue" when she wrote "Run, Run As Fast As You Can" in 1982. The book itself is semi-autobiographical in nature, according to Osborne: "The girl was a lot like me and many of the incidents in the story were similar to happenings in my childhood." The book served as the starting point for Osborne's writing career. Her early work received mixed reviews. Her work includes young adult novels, picture books, retellings of mythology and fairy tales, biographies, mysteries, a six-part series of the Odyssey, a book of American Tall Tales, and a book for young readers about the major world religions.