Karr's Oz-related works are:
- The Gardener's Boy of Oz (1988)
- Maybe the Miffin (1993)
- Fwiirp in Oz (1996)
- The Hollyhock Dolls in Oz (2004).
The Gardener's Boy of Oz is a sequel to Baum's The Scarecrow of Oz. Maybe the Miffin is the tale of Snif the Iffin (from Thompson's Jack Pumpkinhead of Oz) searching for his mate. Karr's Oz works have been illustrated by Melody Grandy.
Beyond the confines of Oz, Karr has written multiple volumes of Arthurian fiction and similarly-themed romance, plus mystery stories, general fiction, and works of scholarship on Oz and other subjects. Her article on Zauberlinda, titled "The Wise Witch and the Wonderful Wizard," appeared in the Spring 2009 issue of The Baum Bugle.