2009-10: Cullen Eddy made his pro debut with the ECHL's Cincinnati Cyclones following his senior season at Mercyhurst College. He had 1 assist and was plus-four with 6 penalty minutes in seven regular season games for the Cyclones. After finishing second in the North Division, Cincinnati won the ECHL's Kelly Cup championship. Eddy skated in eight playoff games — finishing with an even plus/minus, no points and 6 penalty minutes. Eddy played 30 games for Mercyhurst, leading the team with 97 penalty minutes, and had 1 goal with 5 assists.
2010-11: Signed to an AHL contract by Flyers' affiliate Adirondack, Eddy split his first pro season between the Phantoms and the ECHL's Greenville Road Warriors. He played 47 games for the Phantoms and was minus-one with 3 goals, 7 assists and 40 penalty minutes. In 16 games with Greenville he scored 1 goal with 3 assists and was plus-two with 26 penalty minutes.
2011-12: Eddy skated in 54 games for Adirondack in his second AHL season, leading the Phantoms' defensemen in penalty minutes with 130 (four behind team leader Ben Holmstrom). He scored 2 goals with 13 assists and was minus-13 on a Phantoms team that missed the AHL playoffs; finishing fifth in the Northeast Division. Eddy signed a two-year, entry-level contract with the Flyers in July of 2012.
2012-13: Eddy skated in a career-high 70 games with the Flyers' AHL affiliate in Adirondack in his third pro season. He scored 2 goals with 3 assists and was -12 with 120 penalty minutes (third most among Phantoms). Adirondack missed the playoffs after finishing last in the Northeast Division.
Eddy is in his fourth season with the Adirondack Phantoms of the AHL.