Ramona Marquez was born in March 2001. Her career started at the age of five when she was spotted at a party and, despite having no acting training, chosen to play Karen Brockman in the sitcom Outnumbered. Marquez's next major role was Imogen Pollock in the 2009 BBC television movie drama Enid. In 2010 Marquez made her big screen debut playing Princess Margaret in the historical drama film The King's Speech.
At the 2009 British Comedy Awards Marquez won "Best Female Comedy Newcomer", and shared two awards for Outnumbered which were "Best Situation Comedy" and "Best British Comedy 2009". At the 2012 Young Artist Awards she was nominated for "Best Performance in a Voice-Over Role - Young Actress"