2010-11: Josh Sterk played for the Mississauga Senators minor midget AAA team in the Greater Toronto league. In 37 games he scored 20 goals with 19 assists and 40 penalty minutes. Sterk was selected by Kitchener in the fifth round (83rd overall) in the 2011 OHL Priority Draft.
2011-12: Sterk made his OHL debut with Kitchener as a 16-year-old. In 64 regular season games he scored 7 goals with 14 assists and was +3 with 22 penalty minutes.The Rangers finished second behind OHL champion London in the Midwest Division and lost to the Knights in the Western Conference finals. Sterk had 2 assists and was -4 with 13 penalty minutes in 16 playoff games.
2012-13: Sterk had a tough second year in Kitchener — missing time during the regular season due to concussion issues and being a healthy scratch at times during the OHL playoffs. Skating on a line with 2013 NHL Draft picks Justin Bailey (BUF) and Brent Peterson (CAR), he scored 6 goals with 12 assists and was +10 with 18 penalty minutes in 51 regular season games. The Rangers finished third in the Midwest Division and reached the second round in the playoffs. Sterk scored 1 goal and was +1 with 4 penalty minutes in four playoff games.
2013-14: Sterk was acquired by Oshawa for a conditional draft choice in September prior to the season and had a breakout year with the Generals in his third OHL season. He was Oshawa's fourth-leading scorer with 20 goals and 34 assists and was -2 with 67 penalty minutes in 66 regular season games. Oshawa finished first in the East Division and reached the Eastern Conference finals against Central Division champion North Bay. Sterk scored 5 goals with 4 assists and was -2 with 6 penalty minutes in 12 playoff games. In his second year of eligibility he was ranked 84th amongst North American skaters in Central Scouting's final rankings prior to the 2014 NHL Draft.