Upon signing with the Avalanche, Cohen moved directly into the American Hockey League and made his professional debut with the Lake Erie Monsters.
 He finished the 2009–10 season with one assist in three games.

Prior to the 2010–11 season, Cohen attended his first Avalanche training camp and was among the final cuts assigned to Lake Erie on October 3, 2010.
 After starting the season with the Monsters, Cohen was recalled by the injury-depleted Avalanche and made his NHL debut in a 5–0 shutout win against the Dallas Stars on November 6, 2010.
In his ascension to the NHL, Cohen again joined Shattenkirk as a teammate along the blueline.

 
After three games with the Avalanche, Cohen was returned to Lake Erie before being traded to the Boston Bruins for Matt Hunwick on December 29, 2010.
On April 14, 2011, Cohen was called up by the Boston Bruins as a spare for the playoffs, but he did not play so his name was not engraved on the Stanley Cup as a result when the team won the 2011 Stanley Cup Playoffs.
 The Bruins did, however, include Cohen in the official Stanley Cup photo, and he was presented with a Stanley Cup ring.

On June 26, 2013, Cohen signed his first European contract with the Finnish club Ässät.
Five games into the 2013–14 season with Ässät, Cohen left the team to join the San Antonio Rampage of the American Hockey League, for which he would play two games.

After his stint with the Rampage, Cohen joined NESN as a College Ice Hockey Analyst while also completing his degree in History from Boston University.
Cohen signaled a return to ice hockey, and after bouncing around European clubs for a season, Cohen opted to end his professional playing career to pursue a career as a television analyst currently working for NBC Sports Philadelphia, ESPN , NESN, CBS Sports, and American Sports Network.
Upon signing with the Avalanche, Cohen moved directly into the American Hockey League and made his professional debut with the Lake Erie Monsters.  He finished the 2009–10 season with one assist in three games.
Prior to the 2010–11 season, Cohen attended his first Avalanche training camp and was among the final cuts assigned to Lake Erie on October 3, 2010.  After starting the season with the Monsters, Cohen was recalled by the injury-depleted Avalanche and made his NHL debut in a 5–0 shutout win against the Dallas Stars on November 6, 2010. In his ascension to the NHL, Cohen again joined Shattenkirk as a teammate along the blueline.
 
After three games with the Avalanche, Cohen was returned to Lake Erie before being traded to the Boston Bruins for Matt Hunwick on December 29, 2010. On April 14, 2011, Cohen was called up by the Boston Bruins as a spare for the playoffs, but he did not play so his name was not engraved on the Stanley Cup as a result when the team won the 2011 Stanley Cup Playoffs.  The Bruins did, however, include Cohen in the official Stanley Cup photo, and he was presented with a Stanley Cup ring.
On June 26, 2013, Cohen signed his first European contract with the Finnish club Ässät. Five games into the 2013–14 season with Ässät, Cohen left the team to join the San Antonio Rampage of the American Hockey League, for which he would play two games.
After his stint with the Rampage, Cohen joined NESN as a College Ice Hockey Analyst while also completing his degree in History from Boston University. Cohen signaled a return to ice hockey, and after bouncing around European clubs for a season, Cohen opted to end his professional playing career to pursue a career as a television analyst currently working for NBC Sports Philadelphia, ESPN , NESN, CBS Sports, and American Sports Network.
Colby Cohen