[3] Born in Bloomington, Indiana to Atlantic Canadian parents studying abroad in the United States, Fillmore returned to the family's native Nova Scotia at the age of four.

As Member of Parliament for Halifax, Fillmore held a number of additional responsibilities in the House of Commons and in the Government of Canada.

Beginning September 2018, Fillmore was appointed Parliamentary Secretary to the Minister of Canadian Heritage and Multiculturalism, Pablo Rodriguez.

Following his reelection to the House of Commons for the 43rd Canadian Parliament in the October 2019 federal election, Fillmore was appointed Parliamentary Secretary to Canada's Minister of Infrastructure and Communities, Catherine McKenna.

Following his reelection to the House of Commons for the 44th Canadian Parliament in October 2021, Fillmore was appointed Parliamentary Secretary to Canada’s Minister of Innovation, Science and Economic Development, Francois-Philippe Champagne.