2010-11: Shane Conacher made his debut in Canadian A junior hockey — appearing in two games including one playoff contest with the Burlington Cougars — and skated for the Burlington Eagles midget AAA team. He had no points nor penalties playing for the Cougars.
2011-12: Conacher was the leading scorer for the Burlington Cougars in his first OJHL season. He scored 14 goals with 28 assists and 10 penalty minutes in 46 regular season games. The Cougars finished fourth in the West Division and reached the second round in the playoffs. Conacher scored 2 goals with 5 assists and had 2 penalty minutes in nine playoff games. In December he committed to playing college hockey at Canisius College in 2013-14.
2012-13: Conacher was the second-leading scorer for Burlington before a late season trade to eventual league champion St. Michael's in his second OJHL season. He scored 24 goals with 22 assists and 56 penalty minutes in 36 games with Burlington before the trade to the Buzzers. Conacher scored 4 goals with 7 assists in 15 regular season games for St. Michael's and was named the OJHL playoff MVP after scoring 14 goals with 21 assists and 6 penalty minutes in 23 games. He scored 2 goals with 2 assists in four Dudley Hewitt Cup games as St. Michael's just missed a spot in the Royal Bank Cup, falling to the Minnesota Wilderness, 4-3, in overtime in the championship game.
2013-14: Conacher skated for Canisius College, the alma mater of his older brother Sabres' forward Cory Conacher. He appeared in 32 games as a freshman — missing nine games after breaking his jaw in his first college game. Conacher scored 6 goals with 17 assists and was +2 with 12 penalty minutes. After finishing seventh in Atlantic Hockey in the regular season the Griffins advanced to the conference championship game before falling to Robert Morrison, 7-4. Conacher scored a goal and was +2 in the championship game.