Katy grew up in Brighton and was obsessed with drawing from a young age, spending many hours writing and illustrating her own stories, which her father (award-winning illustrator Chris Riddell) collected. Katy rediscovered her love for illustrating children's books after graduating with a BA Hons in Illustration and Animation from Manchester Metropolitan University.

She has worked on a variety of commissions including Pongwiffy by Kaye Umansky (Simon & Schuster), Midnight Feasting by A.F. Harrold (Bloomsbury) and Ever After at the Oxford Story Museum. She lives and works in Brighton.