Kim is an award-winning author/illustrator of children's picture books. Her debut picture book, Mabel and the Mountain, won the 2020 Sainsbury's Children's Book Award and in 2023 her book Gretel the Wonder Mammoth won the Best Illustrated Book in the Waterstones Children's Prize.

After completing a degree in Drama at the University of Exeter, Kim Hillyard spent nine years working as a music journalist for various publications, including NME, Time Out and the BBC. She has also worked as a drama and arts facilitator, delivering assemblies, storytelling and workshops in schools, bookshops and community spaces on everything from phonics to creative writing.