He represents the electoral district of Topsail-Paradise in the Newfoundland and Labrador House of Assembly, for the Progressive Conservative Party.
[3][4] His brother Jim ran as the New Democratic Party candidate in St. John's Centre and was also elected.
[5] Dinn supported Eugene Manning in the 2023 provincial PC party leadership race.
As of September 22, 2024, Dinn serves as the Official Opposition critic for Education and for Children and Youth Services.
Before entering provincial politics Dinn was a director within the Department of Advanced Education, Skills and Labour.