Coming from a family of stage actors, Richardson-Sellers was always close to the theater and started acting from a young age. In 2013, Richardson-Sellers graduated from University of Oxford in Archaeology and Anthropology where she participated in and directed several plays such as Mephisto, Chatroom, and There Will Be Red. After graduating university, she started auditioning and booked her very first role in the highly anticipated Star Wars sequel, Star Wars: The Force Awakens.
After wrapping filming for her role, Richardson-Sellers booked her second role as Rebekah Mikaelson in the CW series The Originals, where the character of Rebekah inhabits a different body after a spell went wrong. Executive Producer Michael Narducci described her performance as having "an incredibly strong sparkle" and "there's a great beauty – not only with physical beauty but there's a great inner beauty – that comes up in her performance. There's also just this incredible strength."
In beginning of March 2015, it was announced that Richardson-Sellers would act in Of Kings And Prophets, ABC's drama pilot written by Adam Cooper and Bill Collage and directed by Jeffrey Nachmanoff, which was filmed in South Africa.
She currently stars as Amaya Jiwe/Vixen in The CW's DC's Legends of Tomorrow.