Mini Grey was given her name after being born in a Mini in a car park in Newport, Wales. She studied for an MA in Sequential Illustration at Brighton under the tutelage of John Vernon Lord. Mini also worked as a primary school teacher in Oxford, where she now lives.

Her books include Egg Drop, The Pea and the Princess (shortlisted for the CILIP Kate Greenaway Medal), Biscuit Bear (winner of the Nestle Children's Book Prize Gold Award), Traction Man is Here (winner of the Boston Horn Book Award and shortlisted for the CILIP Kate Greenaway Medal), The Adventures of the Dish and the Spoon (winner of the Nestle Children's Book Prize Bronze Award and winner of the CILIP Kate Greenaway Medal), and Traction Man meets Turbodog. Mini Grey is one of the Big Picture's ten Best New Illustrators.