Baldry is one of the three authors of the Warrior and Seekers series, along with Kate Cary, Tui T. Sutherland and editor Victoria Holmes who write under the pen name of Erin Hunter. They write a series of books called Warriors, in which wild cats strive for peace in their territories. She also wrote the second and sixth novels for the Seekers series.
She now lives in Reigate with her two cats, Bramble and Sorrel, who are characters in the Warriors books (Brambleclaw and Sorreltail, respectively). She was married to the late Peter Baldry, a scientist, and has two sons, Will and Adam.