Mabon was elected as a town councillor in
Aberystwyth Town Council in 2004. He stood for election to the
British Parliament and
Senedd unsuccessfully on several occasions between 2005 and 2016. He contested the
Brecon and Radnorshire seat at the
2005 general election. He attempted to be selected as Plaid Cymru candidate for
Ceredigion in 2010, but was not successful. He stood for the
Clwyd South Senedd constituency in the 2011 and 2016 elections, and for the identically named
Clwyd South constituency at the 2015 general election. He was later elected as a
Denbighshire County Councillor for
Llandrillo in 2017.
Member of the Senedd (2021 – present) In 2019 it was announced he would be the Plaid Cymru candidate for the
Dwyfor Meirionnydd Senedd constituency in the
2021 Senedd elections, in a selection process involving five other candidates. He was elected, with a majority of 7,096 votes. He had previously said he would remain in place until elections to be held in May 2022. He chairs cross-party groups on
Fisheries and
Aquaculture,
Housing, and Peace and Reconciliation, and is vice-chair of the
North Wales group. He is a member of cross-party groups on
hospice and
palliative care,
human rights,
long COVID,
poverty,
renewable and low carbon energy, rural growth,
stroke and Welsh wool. He is contesting the new
Gwynedd Maldwyn constituency at the
2026 Senedd election, in second place on Plaid Cymru's list, behind
Siân Gwenllian. ==Personal life==