He represented the electoral district of Fredericton West-Hanwell (and previously for Fredericton-Silverwood) until 2018 as a member of the Progressive Conservatives.

[4][5] On June 22, 2016 Macdonald helped to unveil the LAV Memorial for Canadian soldiers killed in Afghanistan in Oromocto.

[6] On March 3, 2024, Macdonald was chosen to be the Conservative Party of Canada candidate for the riding of Fredericton—Oromocto in the upcoming 45th Canadian Federal Election, which is scheduled for October 20, 2025.

Before entering provincial politics, Macdonald served in the Canadian Armed Forces in Bosnia and worked in Iraq.

Macdonald did his graduate studies in England at the London School of Economics where he earned his master's degree in politics as a Mackenzie King Travelling Scholar.