In film, Rhys appeared as Dylan Thomas in The Edge of Love (2008) and as Daniel Ellsberg in The Post (2017) and starred as a cynical journalist in A Beautiful Day in the Neighborhood (2019).

[6] At age 17, after playing Elvis Presley in a school musical, he applied to and was accepted at the Royal Academy of Dramatic Art (RADA) in London.

[10][11] Rhys starred as Benjamin in the 2000 world premiere of the stage adaptation of The Graduate, alongside Kathleen Turner at the Gielgud Theatre in London's West End.

[13] He played the lead role of Darren Daniels in Tabloid and then returned to New Zealand to shoot the epic drama The Lost World for the BBC.

[15] He moved to Santa Monica after being cast in ABC's show Brothers & Sisters as gay lawyer Kevin Walker.

[12] In January 2012, Rhys appeared in a BBC Two two-part drama adaptation of Charles Dickens' last, unfinished novel, The Mystery of Edwin Drood.

In 2012, Rhys reprised Sir Alec Guinness' 1959 double role of John Barratt / Jacques DeGué in a new adaptation of Daphne du Maurier's The Scapegoat.

[18] In 2013, Rhys starred in the television adaptation of the P. D. James novel Death Comes to Pemberley as Jane Austen hero Fitzwilliam Darcy.

One of them involves an adaptation of a book titled Operation Julie, written by Lyn Ebenezer,[22] about the biggest LSD drugs bust in Wales's history; Rhys bought the film rights in December 2010.

[23][24] In 2023, Rhys spoke on a podcast about how he has been working on a potential film about Glyndwr's life and the rebellion, and that the production has been in development for 12 years.

In 2019, the Glan Yr Afon (also Riverside) was put on the market without any buyers, but through a campaign supported by Rhys there was a shares offering for the public which raised £450,000 to save the pub.