[6] Williams first stood for office in Cardiff West against the Welsh First Minister Rhodri Morgan in the 2007 National Assembly for Wales election.

[8][9] Williams was opposed to Brexit prior to the 2016 UK European Union membership referendum,[10] and consistently voted with the Government Whip.

[12] Prior to the 2019 UK general election, Williams was a Special Adviser to the Secretary of State for Exiting the European Union, Steve Barclay.

[19] In November 2020 it was alleged that Williams was napping on the parliamentary benches, and a social media clip suggested that he was not paying attention, or even sleeping.

[20] Williams claimed this was due to a partial deafness in one ear, which he confirmed during a speech on the British Sign Language Bill.

[21][20] In 2022, Williams resigned from his position as Parliamentary Private Secretary, having lost confidence in the Prime Minister, Boris Johnson.

[28][29] On 25 June 2024, the Conservative Party announced it would be withdrawing support for Williams and would no longer devote resources to his campaign.

[30] The result of the 2024 general election for the Montgomeryshire and Glyndŵr constituency was that Williams lost his seat, polling 7,775 votes, and so coming in third place behind Labour (12,709) and The Reform Party (8,894).