Raffey will play a young girl robot called Athena who, with Clooney’s character, a bitter inventor, attempts to get back to Tomorrowland, an alternative universe created by scientist Laurie, in order to save Earth.
Raffey’s previous credits include the title role in Molly Moon: The Incredible Hypnotist, Young Snow White in Snow White and the Huntsman, and Beatrice Selfridge in the ITV's Mr Selfridge.
Tomorrowland will shoot in Vancouver later this year.