Hawthorn lives in Essex and used to attend Beverly Marks Stage School, she also does numerous musical theatre workshops at Spirit Young Performers Company. Hawthorn was in the original cast of the West End production of The Wizard of Oz and was featured in the original recording. In August 2012 Hawthorn took over playing 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 finished her run in Matilda on 1 September 2013 and at the 100th Royal Variety Performance Hawthorn performed part of the song "Naughty" and also met the Queen and Prince Phillip.
She then won the Mousetrap Award for Best Actress, becoming one of the youngest people to win the award. She was also nominated for an Olivier, alongside her fellow cast members, and was featured in the Oliviers 2013 performance alongside Lara Wollington, Elise Blake and Cristina Fray. Hawthorn then joined the cast of The BFG landing the lead role of Sophie in 2014 at the Birmingham Rep alongside Madeleine Haynes and Lara Wollington, finishing her run in early 2015, which included recording a voiceover advert for Free Radio advertising the show. Hawthorn announced that she would be joining Spirit Young Performers Company in April 2016, after attending many workshops, that have received millions of views online and on YouTube.
She recently made her series debut in Campfire Creepers at the Sitges Film Festival in Spain directed by Alexandre Aja and joined by Robert Englund in the cast. It is one of the first ever Virtual Reality 360 horror series and is set for release in October 2017 on the Oculus Store.