In 2009, Duncan was honored with a CBE (Commander of the Most Excellent Order of the British Empire) in the Queen's Birthday Honours List for services to drama.
In 2014, she appeared as Tabitha in the film Birdman, or (The Unexpected Virtue of Ignorance), which won the Academy Award for Best Picture.
Along with her many film and TV roles, she can be seen as Ysabeau De Clermont on the Freeform series A Discovery of Witches (2018-2022) and as Anvaere Damodred on the Prime Video series The Wheel of Time (2023). She can currently be seen as Martha Ellison on the AppleTV+ series The Morning Show.