owen was born in north cornelly, south wales. he trained at the guildford school of acting, made his television debut in the mimosa boys in 1984. in 1985, he appeared in the doctor who serial vengeance on varos as "maldak". his film debut was in war requiem in 1989. He later appeared in knights of god (1989), great expectations (1989), the fifteen streets (1989) and boon (1990) before being cast as will scarlet in the 1991 film robin hood.

he went on to appear in such series as dangerfield, ballykissangel, the thin blue line and the long-running belonging, and later spooks and murphy's law.

in 2006, he appeared in the torchwood episode "countrycide". and in 2006 he had a role in the hbo uk tv movie tsunami: the aftermath. in 2011, teale appeared as ser alliser thorne in game of thrones, the hbo tv adaptation of george r. r. martin's novel series a song of ice and fire, replacing at short notice derek halligan. he reprised this role in season 4, season 5, and season 6.

in 2012, he played dai in the comedy-drama series stella and robert holland, the fictional uk foreign secretary, in the drama series kidnap and ransom. he also plays chief constable osborne in the bbc police drama line of duty. between 2018 and 2022 he played peter knox in a discovery of witches, a series based on the book of the same name by deborah harkness.