[2] He represents the electoral district of St. John's Centre as a member of the Newfoundland and Labrador New Democratic Party.

[1] Dinn won the NDP nomination in St. John's Centre ahead of the 2019 election after incumbent MHA Gerry Rogers opted not to seek re-elected.

[14] He praised the project for the benefits that it would provide for many workers and their families while also claiming that the provincial and federal governments were ignoring the impacts of climate change.

In March 2022, Dinn praised the confidence and supply agreement between the federal NDP and the Liberal Party of Canada.

[15] Dinn initially rejected the possibility of running for the role of NDP leader, instead preferring to only serve in an interim capacity.