In 2010, he was serving as policy analyst at the Department of Human Resources and Skills Development for the federal government before taking a leave of absence to run for the Nova Scotia Liberal Party in Yarmouth.

[5][8] On October 22, 2013, Premier Stephen McNeil appointed Churchill to the Executive Council of Nova Scotia as Minister of Natural Resources.

[15] During the 2021 Nova Scotia Liberal Party Leadership Election, Churchill supported Iain Rankin in his bid to become leader.

In the wake of the Liberal Party's defeat in the 2021 Nova Scotia general election, Churchill became Deputy Leader of the Official Opposition and Health Critic.

[21][22] In the 2024 Nova Scotia general election, Churchill led the Liberals to a third place finish with two seats, behind the PCs and NDP, one of the worst results in their history.