2009-10: Pearson was the second-leading scorer for the Waterloo Siskins in his second season in the GOJHL. In 51 games he scored 29 goals with 41 assists and had 78 penalty minutes. Waterloo finished second in the Midwestern Conference and advanced to the conference semifinals. In 11 playoff games Pearson scored 5 goals with 11 assists and had 20 penalty minutes.
2010-11: Originally selected by Barrie in the 14th round (266th overall) of the 2008 OHL Priority Draft, Pearson skated in 66 of 68 games for the Colts in his first OHL season. Pearson scored 15 goals with 27 assists and was minus-12 with 35 penalty minutes. Barrie missed the OHL playoffs; winning 15 games and finishing with the OHL's worst record. Pearson was not among the 210 North American skaters in Central Scouting's final rankings and was not selected in the 2011 NHL draft in his second year of eligibility.
2011-12: Pearson had a dominant season in the OHL as a 19-year-old and skated for Canada at the 2012 U20 World Junior Championship before suffering a season-ending leg injury in March. He finished as the OHL's third-leading scorer with 37 goals and 54 assists and was plus-21 with 37 penalty minutes. Barrie was one of the top teams in the OHL – finishing second behind Niagara in the Central Division with the league's sixth-best record. Pearson was injured in the Colts' final game of the season against Brampton; suffering a broken fibula. In six games for third-place Canada at the WJC he had 1 goal with 5 assists and was plus-one with 6 penalty minutes. He was invited to the NHL Draft Combine and was ranked 25th amongst North American skaters in Central Scouting's final rankings prior to the 2012 NHL Draft.
Pearson persevered after being passed over in two previous drafts to become a first round pick of the Kings. He improved his offensive game in 2011-12 through a combination of improved skating and added muscle. Pearson also evolved his game into a two-way game that should help him to eventually earn a place in the Kings lineup. It remains to be seen if his offensive game will be as effective at the pro level, but there is reason to believe that Pearson has the drive and determination to make it happen.