His notable television roles include Chris Finch in The Office (2001), Dagmer Cleftjaw in Game of Thrones (2012), and Nikolai Tarakanov in Chernobyl (2019).

[7] He starred as Donald Bamford in the sitcom Goodnight Sweetheart, as Zack in the soap opera Coronation Street, and played ex-soldier Sam Walker in the first series of Spooks.

[citation needed] He has also appeared in the HBO series Chernobyl, and in The Dark Crystal: Age of Resistance for Netflix.

Ineson's Hollywood film credits include First Knight, From Hell, Sex & Drugs & Rock & Roll and a brief role in The Damned United.

[8][9] Also in 2014, he had a small role in the spy film Kingsman: The Secret Service, playing a policeman who interviews Eggsy.

Ineson appeared in a minor role as a First Order officer in the 2017 film Star Wars: The Last Jedi.

[11] Recent roles include The Green Knight (as the title character), Ready Player One, The Ballad of Buster Scruggs, Everybody's Talking About Jamie, The Tragedy of Macbeth, The Northman, Catherine Called Birdy, To Catch a Killer (as the titular serial killer) and The Creator.

In 2009, he narrated the BBC One documentary Series Gears and Tears which follows the characters of British BriSCA Formula 1 Stock Cars.

Ineson filed a lawsuit against Disney in December 2023, claiming that he suffered from permanent shoulder damage due to injuries he sustained while filming the Disney+ series Willow.