Among Power's first television roles were in Life with Mikey and Joe's Wedding. In 2004 Power played the role of series regular Warren on the controversial RTE series The Big Bow Wow. After one season the show was canceled and then 2005 Power was hired to play Garth O’Hara in the RTE Soap Opera Fair City. Power was cast as Frankie in the Irish coming-of-age film Cowboys and Angels. Power was then cast as John in Gilles MacKinnon’s Tara Road, which filmed in Cape Town, Dublin and London. In 2005 Power was asked to read for a new comedy series for the BBC written by and starring Jack Dee. Lead Balloon, initially started on BBC4 and then moved to BBC2 where it ran from 2006-2011, with Power playing Marty, the sardonic writing partner of failed comedian Rick Spleen (Jack Dee). During this time Power also had guest leads on the British television series Moving Wallpaper, Holby City, Doctors, Taking the Flak, and Wild West. During this time Power filmed his first feature film in Played, a series of three with the actor and writer Mick Rossi. Played was produced by John Daly, with an all-star cast and indie film budget, it was originally intended to be a short. The film was shot without the use of a scripted screenplay and the director (Sean Stanek) allowed the actors to improvise a majority of dialogue as he shot the scenes. The film was shot on location in London and Los Angeles and took three years to complete. Rossi then offered Power the role of Rudy in the heist film 2:22, then in 2012 Power starred along Rossi in the psychological thriller A Kiss and A Promise' as the character Charlie Matthews". During this time Power also appeared in minor role with Anthony Hopkins in Fernando Meirelles interrelationship film 360. In 2011 Power returned to Dublin to film Honeymoon for One with Nicollette Sheridan. In late 2012, Power starred alongside Ryan Sampson, Kate Miles and Diane Morgan as Colby Brown in the mock reality/hidden camera show E4’s The Work Experience. Each episode, partially scripted and improvised was shot in real time for 3 consecutive work days in a fictitious London PR firm. Each week, new interns were brought in believing they were participating in a documentary programme. At the end of filming The Work Experience, Power was cast as the vampire hunter Peter Vincent in 20th Century Fox’s reboot Fright Night 2 filmed on location in Transylvania and Bucharest, Romania. This was followed by Steve Barker ‘s popular zombie film The Rezort alongside Dougray Scott and Martin McCann. Following The Rezort, Power was cast as a lead role alongside actors Billy Boyd, Alice Lowe, and Eline Powell in the Lennox Brothers debut feature Stoner Express (a.k.a. AmstarDam), a marijuana-fuelled fairytale shot in Amsterdam and London. In the film notorious author and cannabis smuggler Howard Marks played himself, this was his last film before he died in 2016. In 2016, Power created, directed and shot 10 episodes of Chinese Girls in London, a short format comedy series with an all-Chinese cast. The show was optioned by Roughcut Tv Productions with the pilot episode to be shown on BBC 3 in late 2017. During this time, Power was cast as Mitch, in Mick Jackson’s Bafta-nominated Denial, followed up by Lt Brett Biggle in Brad Pitt’s satirical war film, War Machine. In 2017 Power was reunited with Woody Harrelson working on his directorial debut Lost in London. The film was the first ever, to be shot in a single take, with one camera and streamed live to audiences in over 500 American theatres. Power followed this up with a role in Mark Strong’s series Deep State, which was filmed through late 2017 and released at the end of 2018. In 2019, Sean teamed up with Irish production company Wytao Film's William Morgan and Vincent Walsh to shoot the award winning comedy Double Denim. In early 2020 he was cast as Bradley in Anna Paquin's series "Flack".