2009-10: Cory Conacher led all scorers in the NCAA's Atlantic Hockey league while skating for Canisius College as a junior. Playing in 35 of 37 games for the Golden Griffins, he scored 20 goals with 33 assists and was plus-nine with 36 penalty minutes. Canisius finished in fifth place and reached the semifinals in the conference tournament. Conacher was named to Atlantic Hockey's first all-star team.
2010-11: Conacher, made his pro hockey debut, skating with three different pro teams after completing his senior season at Canisius. He signed an AHL contract with Rochester and appeared in two games with the Amerks. After a three-game stint with the ECHL's Cincinnati Cyclones he finished the year with the AHL's Milwaukee Admirals. In seven AHL games between Rochester and Milwaukee he scored 4 goals with 2 assists and was minus-two with 4 penalty minutes. In seven AHL playoff games with Milwaukee he was plus-two with 1 assist and 6 penalty minutes. Conacher scored 5 goals in his first two games with the Cyclones and was plus-four with 7 points in 3 ECHL games.
2011-12: Conacher was invited to Lightning training camp and signed an AHL contract with Tampa Bay affiliate Norfolk. He led the AHL with 39 goals and had 41 assists (his 80 points were second only to Hershey's Chris Bourque (93)). Conacher was plus-19 and third on the Admirals with 114 penalty minutes. Norfolk finished first in the East Division and won the AHL's Calder Cup. Conacher scored 2 goals with 13 assists and was plus-six with 28 penalty minutes in 18 playoff games. He was award the Les Cunningham MVP trophy and named the AHL's Rookie of the Year. He signed a two-year, entry-level contract with Tampa Bay in March, 2012.
2012-13: Conacher burst onto the NHL scene as a rookie with Tampa Bay following the end of the lockout, scoring 7 goals with 11 assists in his first 20 games. The Senators obtained Conacher in April 2013 in the trade that sent Ben Bishop to the Lightning. In 47 regular season games between the two teams Conacher scored 11 goals with 18 assists and was +3 with 20 penalty minutes. He skated in eight of Ottawa's ten playoff games, scoring 3 goals and finishing -2 with 31 penalty minutes. Conacher played 36 AHL games with Syracuse during the lockout. He scored 12 goals with 16 assists and was +3 with 20 penalty minutes.
Conacher was claimed off of waivers by the Buffalo Sabres at the 2014 Trade Deadline.