Smyth became a Labour party organiser in 2003. In 2008, he was appointed general secretary of the Scottish Labour Party, succeeding Lesley Quinn. In September 2012, Scottish Labour announced that Smyth would step down from the position at the party's conference in the following month. In
2007, Smyth was elected to
Dumfries and Galloway Council, representing Nith Ward. He was re-elected to this position in
2012. In October 2013, a Labour/SNP coalition was formed on Dumfries and Galloway Council and Smyth was appointed Chair of the Planning, Housing and Environment Committee.
Member of the Scottish Parliament In the
2016 Scottish Parliament election, Smyth was elected as an
additional member, representing the
South Scotland region. He served as
Scottish Labour Spokesperson for Transport, Infrastructure and Connectivity under
Richard Leonard from 2017 to 2021. Smyth nominated
Anas Sarwar in the
2021 Scottish Labour leadership election. After the leadership election, Sarwar appointed Smyth as
Scottish Labour Spokesperson for Constitution, Europe and External Affairs. At the
2021 Scottish Parliament election, Smyth was supported as a
Labour Co-operative candidate for the first time. He contested the constituency seat of
Dumfriesshire, where he came a distant third with 4,671 votes (11.4%). Smyth was returned on the regional list for South Scotland. Smyth backed the UK Government’s decision to introduce means-testing for the
Winter Fuel Payment, voting in the Scottish Parliament against calls to reverse the decision. Smyth was selected in April 2025 as the Labour candidate for Dumfriesshire at the
2026 Scottish Parliament election.
Criminal charges and suspension from Labour Smyth was suspended from the Labour Party on 20 August 2025, after being charged with possession of indecent images of children, following the search of a property in Dumfries on 5 August. On 28 August, the
Daily Record reported that Smyth would also be charged with placing a hidden camera in a toilet of the Scottish Parliament and has had his parliamentary pass deactivated. He denied the allegations. Smyth was granted bail in October 2025. Whilst on bail, he was charged with drink driving; his trial was delayed on 6 May 2026. == Personal life ==