2009-10: Josh Morrissey was selected by the Prince Albert Raiders in the first round (sixth overall) of the 2010 WHL Bantam Draft after skating for Calgary Royals Gold and being named the top bantam defenseman in southern Alberta.
2010-11: Morrissey made his WHL debut skating in five games with Prince Albert, spending most of the season with the Calgary Royals midget AAA team and competing for Team Alberta in the Canadian Winter Games. He was minus-three with no points and four penalty minutes in his brief time with the Raiders. Morrissey scored 17 goals with 22 assist and had 11 penalty minutes in 30 games for the Royals. In six AMHL playoff games he scored 1 goal with 3 assists and 10 penalty minutes. Playing for Team Alberta, which won the bronze medal at the CWG, he scored 1 goal with 3 assists and had 10 penalty minutes in six games.
2011-12: Morrissey skated in 68 games for Prince Albert in his first full WHL season and competed in the 2012 U17 World Hockey Challenge and U18 World Junior Championship tournaments. He scored 10 goals with 28 assists and was minus-two with 60 penalty minutes for the Raiders, who missed the playoffs; finishing with the WHL's worst record. Skating for Canada Pacific at the WHC, Morrissey scored 1 goal with 1 assist and and had 10 penalty minutes. He played for bronze medal-winning Canada at the U18 WJC and had 3 assists in seven games; finishing minus-one with 22 penalty minutes.
2012-13: Morrissey was the leading scorer amongst defensemen for Prince Albert in his second season as the Raiders finished with a winning record for the first time since 2003-04. He scored 15 goals with 32 assists and was plus-14 with 91 penalty minutes. Prince Albert was second to Saskatoon in the East Division. Morrissey had 1 assist and was minus-three with 9 penalty minutes in the four-game playoff series with Red Deer. He joined Team Canada for the 2013 U18 World Junior Championship and scored 2 goals with 4 assists and was plus-seven in the first four games of the tournament. Morrissey was ranked 11th amongst North American skaters in Central Scouting's mid-term rankings prior to the 2013 NHL Draft, and 27th in the CSS final rankings.