[5] After graduating, Turner appeared in several theatre plays, including The Plough and the Stars, Romeo and Juliet, and A Cry from Heaven.

[17][18] Turner played the vampire John Mitchell on the supernatural drama programme Being Human[19][20] during the first three series from 2009 to 2011, for which he received widespread praise.

[21][22][23] His role on Being Human brought Turner to the attention of Sir Peter Jackson, who cast him as the dwarf Kíli in The Hobbit trilogy (2012–2014).

[7] In 2013, Turner also portrayed shadowhunter-turned-werewolf Luke Garroway in the film adpation of Cassandra Clare's The Mortal Instruments fantasy series.

He acted opposite of Lily Collins, Jamie Campbell Bower, Lena Headey, Robert Sheehan, and Jonathan Rhys.

Turner took on the role of Glenn Lapthorne, a professional tennis coach accused of sexually abusing his former underage protege (portrayed by Ella Lily Hyland), in the 2023 British drama Fifteen-Love.

He starred alongside David Tennant, Victoria Smurfit, Alex Hassell, Bella Maclean, Nafessa Williams, Katherine Parkinson, and Danny Dyer.