Widdicombe was born on 8 April 1983 in Hammersmith, London, but grew up in Haytor Vale, near Widecombe in the Moor on Dartmoor in Devon.

[3][4] He attended Ilsington Church of England Primary School[5][6][7][8] and South Dartmoor Community College, later studying sociology and linguistics at the University of Manchester.

[12] In 2010, Widdicombe worked as a contributor for the Dora the Explorer magazine,[13][14] and in 2011 he performed his debut solo show "If This Show Saves One Life..." at the Edinburgh Festival Fringe, and was subsequently nominated for Best Newcomer by the Foster's Edinburgh Comedy Awards[15] and for the Malcolm Hardee "Act Most Likely to Win a Million Quid" Award.

In May 2013, Widdicombe was a guest on the second series of Dara Ó Briain: School of Hard Sums with Marcus Brigstocke.

[27] Widdicombe won Celebrity Mastermind broadcast 31 December 2013 with a score of 24, on the specialist subject of his favourite band, Blur.

[29][30] On 1 July 2014, the BBC announced Widdicombe would be joining its Radio 5 Live team from August 2014 as the new host of Fighting Talk along with Georgie Thompson.

[31][32] In August 2014, Widdicombe starred in the BBC Three Comedy Feeds pilot Josh, which he co-wrote with comedian Tom Craine and which was directed by David Schneider.

[40] The show regularly featured contributions from comedians James Acaster, Nish Kumar, Joe Lycett and several others along with occasional interjections and background laughter by XFM's "Intern Charles".

[40] In December 2015, Widdicombe announced that he was a team captain on the BBC Two comedy panel show Insert Name Here, appearing alongside Richard Osman and host Sue Perkins.

[46] Guests include footballers such as Iain Dowie, Darren Huckerby, Pat Nevin and Matthew Le Tissier as well as comedians such as Elis James, Tom Parry, Ivo Graham and Matt Forde.

[47] In 2019 Widdicombe began hosting panel show Hypothetical with James Acaster for UK television channel Dave.

[48] In 2021, it was announced that Widdicombe had written a book: Watching Neighbours Twice a Day... How '90s TV (Almost) Prepared Me for Life, published in September 2021.

[48][17][56] The couple lived for a considerable amount of time in Shoreditch, before moving to a "sleepier" area of east London to raise their children.