2011-12: Kyle Pettit skated for the London Junior Knights Gold minor midget team in Ontario. He scored 14 goals with 18 assists and 14 penalty minutes in 30 regular season games. In 11 playoff games he scored 4 goals with 4 assists and 12 penalty minutes. The Junior Knights skated in the 2012 OHL Cup and in five games Pettit scored 1 goal with 1 assist and 6 penalty minutes. He was selected by the Erie Otters in the second round (27th overall) in the 2012 OHL Priority Draft.
2012-13: Pettit made his OHL debut as a 16-year-old and skated in 67 of 68 games for Erie in his rookie season. He scored 3 goals with 3 assists and was minus-10 with 21 penalty minutes. Erie finished last in the Midwest Division and missed the playoffs after finishing with the OHL’s second-worst record.
2013-14: Pettit played a two-way role for Erie in his second OHL season as the Erie Otters were one of the big turnaround stories in junior hockey; finishing second in the Midwest Division and reaching the OHL playoff semifinals. Overshadowed by high profile scorers like rookie Connor McDavid, he scored 5 goals with 5 assists in 53 games — missing 15 games due to a shoulder injury — and was +3 with 24 penalty minutes. In nine playoff games he was minus-3 with no points and 2 penalty minutes; missing five games after suffering a leg injury. Pettit was ranked 161st amongst North American skaters in the Central Scouting final rankings and was selected by Vancouver in the sixth round (156th overall) in the 2014 NHL Draft.