Hopper was voted Expert Choice by The Stage at the Rose Bruford Acting Showcase June 2006.

Hopper was cast in As You Like It at the Watford Palace Theatre and has appeared in various television programmes and films such as Saxon, Casualty, Kingdom and Doctors. Hopper portrayed Marcus in a comedy-horror film, Tormented about a bullied teenager who comes back from the dead to take revenge on his classmates. The film was made by BBC Films, Slingshot & Forward Films and was released internationally by Pathe, on 22 May 2009 in the UK. Hopper played Sir Percival in the BBC series Merlin. On 3 June 2012, he appeared as himself on the game show Deal or No Deal, opening a box for a Celebrity special involving his friends, pop band McFly. He stars in the feature film Cold [1] filmed in Ireland in 2012 and due to be released at festivals in 2013. Hopper has become the first actor to join new Starz series Black Sails. The pirate drama – exec produced by Michael Bay – serves as a prequel to Robert Louis Stevenson's Treasure Island. He joined the cast of the HBO series Game of Thrones in season 7 as Dickon Tarly (replacing Freddie Stroma who had previously appeared in the role in season 6).

Hopper married British Actress Laura Hopper (née Higgins) on 7 June 2014. On 1 June 2015, the couple had their first child, son Freddie Douglas Hopper.