Okonedo trained at the Royal Academy of Dramatic Art. She has worked in a variety of media including film, television, theatre and audio drama. She performed in "Scream of the Shalka", a webcast based on the BBC television series "Doctor Who" as Alison Cheney, a companion of the Doctor. As well as providing the character's voice, Okonedo's likeness was used for the animation of the character. In 2010, Okonedo portrayed Liz Ten (Queen Elizabeth X) in the BBC TV series "Doctor Who" episodes "The Beast Below" and again briefly in "The Pandorica Opens".