He is best known for starring as Arthur Pendragon in the BBC series Merlin (2008–12), Damien Thorn in Damien (2016), Varga in Underworld: Blood Wars, Giuliano de' Medici in Medici: The Magnificent (2018–2020), and Lieutenant Colonel Felix Sparks in The Liberator (2020).

[4] In 2008, James appeared in an episode of Lewis, then played the part of Ben Davis in the BBC Three comedy-drama film Dis/Connected.

[7] James went on an exploration of Arthurian legends for BBC Wales, The Real Merlin & Arthur, in 2009.

[8] In 2014, James guest-starred as Edgar in the fourth season of the Emmy Award-winning political thriller television series Homeland.

[13] This is the first project produced in Trioscope, a new enhanced hybrid technology that combines state-of-the-art CGI with live-action performance.