Cartwright was born on 14 March 1981 in Erdington, West Midlands. He has an older brother, Che Cartwright, who is also an actor.
He played Gary Bell, a character with autism, on the Syfy television series Alphas (2011–2012). To prepare for the role, Cartwright consulted with people who worked with people with autism, watched documentaries, read blogs created by people with autism, and books from authors with autism, such as Temple Grandin and Daniel Tammet. Cartwright's portrayal of Bell has earned praise from the neurological science community, crediting his complexity for eschewing stereotypes of autism previously displayed in mass media.
