 During the 2017–18 season, having being placed on waivers by the Wild approaching the trade deadline, Stewart was claimed by the Calgary Flames on February 26, 2018.He appeared in 7 regular season games scoring 3 points as the Flames missed out on the post-season.As a free agent from the Flames, Stewart was un-signed over the summer, before opting to continue his professional career in Europe agreeing to a one-year deal with Slovakian club, HC Slovan Bratislava of the Kontinental Hockey League (KHL) on September 26, 2018.