[1][2] He is the son of Philip Taptiklis, a business consultant, and Jane (née Martin), who worked for the National Health Service.

That same year, he also played James, an obnoxious night club rep, in the British comedy The Inbetweeners Movie (2011).

In 2012 James appeared in the miniseries Room at the Top as Jack Wales and ITV's Case Sensitive as Aiden Harper.

[19][20] James starred as Detective Walter William Clark Jr. in the American crime-drama series Golden Boy (2013), which aired for one season.

[21] James' breakthrough role was his portrayal of Tobias "Four" Eaton in Divergent (2014), a film adaptation of Veronica Roth's novel of the same name.

[24] James starred alongside Amber Heard, Billy Bob Thornton and Jim Sturgess in the film adaptation of London Fields,[25] and in the indie drama The Benefactor (2015), with Richard Gere and Dakota Fanning.

[28] James produced and appeared in the 2020 science fiction film Archive, playing a robotics scientist working on a secret project involving building a prototype based on his dead wife.

The Hollywood Reporter's Angie Han described James's portrayal of the titular time traveler "dashing and a little sardonic" and highlighted his and co-star Rose Leslie's "inability to generate any real sparks between them".

[31] In 2024 he starred as Edward "Eddie" Horniman, Duke of Halstead, alongside Kaya Scodelario, Daniel Ings, and Ray Winstone, in the Guy Ritchie television series The Gentlemen, released on Netflix.

[37] He has since been a supporter of refugees' rights and called for greater humanitarian aid for people displaced by the Syrian Civil War.