He served as Member of Parliament (MP) for the constituency of City of Chester from winning the seat in the 2015 general election[2] until his resignation in October 2022 following sexual misconduct allegations.

[18] On 21 October 2022, The Independent Expert Panel recommended that Matheson be suspended from the House of Commons for four weeks over allegations of "serious sexual misconduct" towards a junior member of staff.

[22][23][3] Matheson continued to deny any sexual misconduct but said he felt obliged to resign for health and family reasons.

Warning of Brexit extremist plans "to tie the UK to Trump's US", Matheson called for the defence of the "values of fairness, decency and internationalism".

[31] Despite his stated views regarding Brexit, Matheson voted in Parliament to empower the Prime Minister to trigger Article 50 by giving notification of the United Kingdom's intention to leave the European Union.