Lucas first came to prominence on the comedy panel show Shooting Stars, in which he portrayed scorekeeper George Dawes from 1995 to 2009.

He has also appeared in films, including Astro Boy (2009), Alice in Wonderland (2010), Bridesmaids, Gnomeo & Juliet (both 2011), Small Apartments (2012), Paddington (2014), and Wonka (2023).

[9] He again appeared with Reeves & Mortimer in the BBC TV series Randall & Hopkirk (Deceased) and Catterick, in a variety of roles.

In 1999, Lucas paired with David Walliams, with whom he had already worked in Mash and Peas and Sir Bernard's Stately Homes, to create Rock Profile, a comedy show spoofing famous musical personalities.

Among the many characters he plays in the series, which he writes and acts in along with David Walliams, are apparently "disabled" Andy Pipkin, teenage Bristol chav Vicky Pollard, homophobic homosexual Daffyd Thomas, and insensitive slimming club organiser Marjorie Dawes.

[13] In 2005, he took his first role in a television drama, a supporting part as a Venetian duke in the BBC historical serial Casanova, written by Russell T Davies.

He has appeared in Kath & Kim and Neighbours (the latter alongside David Walliams as Little Britain characters Lou and Andy), as well as a cameo role, playing 'Chris' or 'Jammy' at the wedding fayre, in the BBC Three sitcom Gavin & Stacey.

[15] Starting in February 2010, Lucas began hosting his own radio show, And The Winner Is, in which he handed out a fictional series of awards based on nominations by his guests.

Also in 2011, Lucas lent his voice to the CGI film Gnomeo and Juliet and he played a small role as the roommate of Kristen Wiig in the comedy Bridesmaids.

Unlike their previous work, Little Britain, this new show concentrated solely on the airline industry, with Walliams and Lucas each portraying several characters.

In a BBC Three interview aired on February 9, 2011, it was revealed that the creators had considered including Carol Beer, the travel agent character from Little Britain.

Lucas also starred in the dark comedy Small Apartments released in February 2013 alongside James Caan, Billy Crystal, Johnny Knoxville, and Juno Temple with other cameo performances by notable actors.

[21] From 2 July to 25 August 2018, Lucas played Bill Snibson in a revival of Me and My Girl at Chichester Festival Theatre.

[23][needs update] In 2021, Lucas continued to sit in for Zoe Ball and host the Radio 2 Breakfast Show.

[24] From 10 August to 30 November 2019, Lucas appeared in Les Misérables at the Gielgud Theatre in London's West End, playing the role of Monsieur Thénardier in a fully staged concert adaptation of the musical.

On 20 December 2019, Lucas returned to the role at the Sondheim Theatre, after actor Gerard Carey contracted vocal damage through pneumonia and was forced to pull out.

[25] In March 2020, he became the new co-host of the Channel 4 and Love Productions television show The Great British Bake Off, taking over from Sandi Toksvig.

Lucas also wrote a children's picture book based on "Thank You, Baked Potato", published by Egmont and all proceeds again go to Feed NHS.

[29] Lucas is a patron of the Karen Morris Memorial Trust, a UK charity for leukaemia patients and their families.