Thomas represented Canada at the 2010 IIHF World U18 Championships. He had two goals and one assist in six games for Team Canada. He was invited to the selection camp for Canada's National Junior Team for the 2012 World Junior Ice Hockey Championships. In November 2017, as part of the Olympic evaluation process, Thomas travelled to Finland as a member of Team Canada to participate in the Karjala Cup. In the final Olympic evaluation tournament, Thomas won the Spengler Cup with Team Canada in Davos, Switzerland on December 31,2017. Thomas was then selected as a member of Canada's team for the 2018 Winter Olympics where he earned the bronze medal.