Accompanied by Demi Moore, who played villain Madison Lee in Charlie's Angels: Full Throttle, the women posed for photos while cheering on Liu.
Our favourite ladies looked chic with Barrymore, 44, and Liu, 50, dressing up for the occasion in flowing floral dresses, while Diaz, 46, dressed down in jeans, and a long white blazer.
Liu's 3-year-old son Rockwell was also at the ceremony and on hand to congratulate his actress mum, with one of the sweetest moments of the ceremony being when the pair embraced.
Congratulations Lucy!