[6][7][2] Prior to moving full-time to comedy, James was guitarist with the Cardiff-based indie/punk band Heck, fronted by Jemma Roper.

[9] James commenced his role as Rex Jones, an old caretaker who is a post-Marxist with a health-and-safety obsession, in the live show Chris Corcoran's Committee Meeting in 2009.

The show, conceived by Welsh comedian Chris Corcoran, was held for three years at the Muni Arts Centre.

Corcoran explained in 2014: "We would write each show from scratch in the space of five days and the first time we'd perform it would be in front of the audience.

Supporting Gilbert, James experienced performances before audiences of over 1,500 people and he later said that he felt like a "pop star" when he walked on stage during the tour.

James performed alongside partner Isy Suttie, as well as comedians Henry Paker and Mike Wozniak.

[20] On 2 April 2019, it was announced that James and Robins will be hosting a new Friday afternoon radio show on BBC 5 Live starting 31 May.

In the show, which also features Nadia Kamil and Ben Partridge, various figures from Welsh history are comically compared to each other in an attempt to identify the most heroic.

[24] A pilot episode of Ankle Tag aired on BBC Radio 2 in 2015[25] in which James played the lead alongside Steve Speirs and Katy Wix.

James also makes occasional appearances on The Guardian's Football Weekly podcast, usually to talk about the performances of the Welsh national team.

James presented early episodes of the S4C music television programme Bandit[29] and has appeared in segments of Hwb, S4C's Welsh-learners program.

[36] In 2015 he appeared on The Really Welsh Christmas Quiz on BBC One Wales, alongside fellow comedians Chris Corcoran, Miles Jupp and Omar Hamdi.

[45] In 2024 the show won the "Radio Times Moment of the Year" award at the ARIAS for an edition in which John Robins revealed his struggle with alcohol addiction and his journey to recovery.

[46] James is a supporter of Swansea City and Wales, and has an extensive collection of retro shirts of both teams.

He said in 2010 that the worst thing about being a comedian is when the timing of Swansea City games clashes with his live show commitments.

[48] James married his longtime partner, actress, comedian and musician Isy Suttie, on 17 August 2024.