2010-11: Matt Mistele skated for the Whitby Wildcats midget minor AAA team in Ontario. He scored 43 goals with 34 assists and had 50 penalty minutes in 60 games. Mistele was selected by Plymouth in the second round (33rd overall) of the 2011 OHL Priority Draft.
2011-12: Mistele skated in 12 of 13 playoff games for Plymouth after seeing limited ice time with the Whalers during much of his first OHL season. In 28 regular season games he scored 3 goals with 2 assists and was +2 with 33 penalty minutes. The Whalers finished first in the West Division and reached the second round in the playoffs. Mistele scored 2 goals with 3 assists and was +1 with 11 penalty minutes in the playoffs.
2012-13: Mistele led the Whalers with 34 goals and was one of three players to skate in all 68 regular season games in his second season with Plymouth. He finished +32 and had 26 assists and 69 penalty minutes as Plymouth again finished first in the West Division. The Whalers reached the Western Conference finals against OHL champion London. Mistele appeared in 9 of 15 playoff games — receiving a six-game suspension for a hit to the head in the first round against Sarnia. He scored 3 goals with 2 assists and was an even plus/minus with 8 penalty minutes in the playoffs.
2013-14: Mistele returned to Plymouth for his third season with the Whalers. He was selected to play for Team Cherry in the 2014 CHL/NHL Top Prospects Game.