Carmichael studied at Macquarie University in Sydney, where she took creative writing courses and was awarded the university prize for playwriting. As a result, she was selected for the inaugural National Institute of Dramatic Art (NIDA) playwriting program. Subsequently, Carmichael began a career as an English teacher, during which time she wrote a series of comedy plays, published under the title Is That a Muffled Shriek? In the mid-1980s she left teaching to become a full-time writer.
Carmichael says of her writing for children and young adults: 'In my novels I explore the meaning of personal identity, the impact of technology upon the individual and the directions in which our society may go.'
Under the name 'Claire McNab', Carmichael has also written many detective novels for adults, including the Detective Inspector Carol Ashton series. Her first adult mystery, Lessons in Murder, set in the Northern Beaches area of Sydney, was published in the United States in 1988.
Carmichael is also the author of several English textbooks, self-help books, and is the joint editor of a book on desserts. She has lived in Los Angeles since 1994, and has taught with the UCLA Extension Writers' Program, but visits Australia at least once a year. The protagonist of her Kylie Kendall detective series is also an Australian living in Los Angeles.