As a junior, Reinhart played four seasons at centre with the Ice between 2008 and 2012 where he scored 235 points in 266 games. Following a 27-point campaign as a 16-year-old in 2008–09, he improved to 51 points in 2009–10 and earned a spot with the Canadian under-18 team at the 2010 IIHF World U18 Championships. Reinhart appeared in six games in the tournament, scoring one assist for the seventh-placed Canadians. Reinhart was selected in the third round (63rd overall) at the 2010 NHL Entry Draft by the Calgary Flames, the same franchise that drafted his father 12th overall in 1979.