Katherine Kurtz was born during a Florida hurricane, and likes to regard this as an auspicious introduction to the world. She read honours humanities at the University of Miami, from which she received a B.S. in chemistry, and attended medical school for a year before deciding she would rather write about medicine than practice it. She completed an M.A. in medieval English history at UCLA while writing her first two novels and working as an instructional designer for the Los Angeles Police Academy, and continued her police work for another ten years before shifting to full-time writing.

In addition to her many works in the Deryni universe, beginning with Deryni Rising and now numbering well over a dozen, she has written several novels of the sort she refers to as "crypto-history" (the secret story behind what is written in the history books) set during WW II (Lammas Night) and the American War for Independence (Two Crowns for America). There was also a science fiction novel thrown in there. In addition, partnered with Deborah Turner Harris, she has written five books for Ace in her Adept series of occult detective thrillers, set in present-day Scotland, and two books exploring the Scottish War of Independence: the Knights Templar, the Stone of Destiny, William Wallace, and Robert the Bruce. A more recent departure from her usual subject matter is a whimsical fantasy set in modern-day Dublin, St. Patrick's Gargoyle, which appeared in 2001.