2007-08: Morrison was chosen in the sixth round, 120th overall, of the 2008 OHL Priority Selection by the Kitchener Rangers.
2008-09: Morrison split his time between the OHL’s Kitchener Rangers and the GOJHL’s Kitchener Dutchmen. In 9 games for the Rangers, Morrison compiled a 4.62 goals-against average, a .860 save percentage, and a 2-2-0 record. In 10 games for the Dutchmen, he posted a 2.91 goals-against average and a .895 save percentage.
2009-10: Morrison again split time between the Rangers and the Stoney Creek Warriors of the GOJHL. In 11 games for the Rangers, Morrison compiled a 3.33 goals-against average, a .896 save percentage, and a 6-2-2 record. Morrison also played in 1 playoff game for the Rangers. In 20 games for the Warriors, Morrison posted a 2.05 goals-against average and a .918 save percentage.
2010-11: In 27 games for the Rangers, Morrison compiled a 2.65 goals-against average, a .912 save percentage, and a 15-6-3 record. In 3 playoff games, Morrison compiled a 2.33 goals-against average and a .939 save percentage.