Conacher went undrafted out of Canisius College, where he played four years (2007-11) and set 12 school records, including career points (147), goals (62), game-winning goals (12) and single-season points (53; 2009-10).

On July 6, 2011, Conacher signed a contract with Norfolk of the American Hockey League. He had 80 points (39 goals, 41 assists) in 75 games in 2011-12, helping Norfolk win its first Calder Cup championship and won the Les Cunningham Award as the AHL's most valuable player.

Conacher signed a two-year, two-way contract with the Tampa Bay Lightning on March 1, 2012. He made his debut with the Lightning on Jan. 19, 2013 and scored his first goal and had an assist in a 6-3 win against the Washington Capitals. He had 24 points (nine goals, 15 assists) in 35 games before being traded to the Ottawa Senators on April 3, 2013 for goaltender Ben Bishop. With the Senators, he had five points (two goals, three assists) in 12 games.

In 2013-14, Conacher had 20 points (four goals, 16 assists) in 60 games for Ottawa, but was waived on March 4, 2014. He was claimed the following day by the Buffalo Sabres and had six points (three goals, three assists) in 19 games.

On July 1, 2014, he signed a one-year, one-way contract with the New York Islanders and had three points (one goal, two assists) in 15 games before he was waived on Dec. 12, 2014. He was assigned to Bridgeport of the AHL after clearing waivers.

On March 2, 2015, Conacher was traded to the Vancouver Canucks and assigned to Utica of the AHL.

After spending the 2015-16 season playing for Bern in the Swiss Hockey League, Conacher signed a one-year, one-way contract with the Lightning and had four points (one goal, three assists) in 11 games in 2016-17. In 2017-18, he had 12 points (eight goals, four assists) in 36 games and no points in two games in the Stanley Cup Playoffs.

NOTES & TRANSACTIONS

• AHL All-Rookie Team (2012)
• AHL Second All-Star Team (2012, 2017)
• Dudley "Red" Garrett Memorial Trophy (AHL -- Rookie of the Year) (2012)
• Willie Marshall Award (AHL - Top Goal-scorer) (2012)
• Les Cunningham Award (AHL - MVP) (2012)
• Signed as a free agent by Norfolk (AHL), July 5, 2011.
• Signed as a free agent by Tampa Bay, March 1, 2012. Traded to Ottawa by Tampa Bay with Philadelphia's 4th round pick (previously acquired, Ottawa selected Tobias Lindberg) in 2013 NHL Draft for Ben Bishop, April 3, 2013.
• Claimed on waivers by Buffalo from Ottawa, March 5, 2014.
• Signed as a free agent by NY Islanders, July 1, 2014.
• Traded to Vancouver by NY Islanders for Dustin Jeffrey, March 2, 2015.
• Signed as a free agent by Bern (Swiss), July 1, 2015.
• Signed as a free agent by Tampa Bay, July 13, 2016.