Hawthorn was in the original cast of the West End production of The Wizard of Oz and was featured in the original cast recording. In August 2012, Hawthorn landed the role of Matilda in Matilda the Musical, taking over from Cleo Demetriou, Jade Marner, Isobelle Molloy and Eleanor Worthington Cox. In her run, Chloe, alongside her fellow Matilda's, became judges on the CBBC and BBC One programme, Junior Masterchef. Hawthorn performed with the cast at the 100th Royal Variety Performance where she performed part of the song "Naughty" and also met the Queen and Prince Philip. She then won the Mousetrap Award for Outstanding Female Performance for her portrayal, becoming one of the youngest people to win the award. She was also nominated for an Olivier Award, alongside her fellow cast members, and was featured in the Oliviers 2013 performance alongside Lara Wollington, Elise Blake and Cristina Fray. Hawthorn finished her run in Matilda on 1 September 2013.