Dornan was born in Belfast in 1982. His father, Jim Dornan, is a doctor. He attended Methodist College Belfast, where he first met David Alexander, his songwriting partner in Sons of Jim. He later attended university but dropped out to pursue a modelling career instead when he was approached by the Select agency. Successful campaigns in Britain and the United States followed. He has made appearances in GQ and Attitude magazines. On the set of the Asprey photoshoot he met English actress Keira Knightley, who introduced him to her agent at PFD. Dornan has since appeared in the Sofia Coppola film, Marie Antoinette playing Axel von Fersen. He co-stars with Kirsten Dunst, Jason Schwartzman, Steve Coogan and Shirley Henderson.