Selected by the Colorado Avalanche in the second round (No. 61) of the 2002 NHL Draft, Boychuk's pro career started in 2004-05 with Hershey of the American Hockey League.

That was the beginning of a five-year run in the AHL that included stops in Lowell, Albany, Lake Erie and Providence. During that span he debuted with Colorado on Jan. 5, 2008 and played four NHL games, but was traded to the Boston Bruins on June 24 of that year.

Boychuk experienced a breakthrough season with Providence in 2008-09. He led AHL defensemen in goals (20), assists (45) and points (65), and won the Eddie Shore Award as the top defenseman in the league while earning First-Team All-Star status. He scored his first NHL goal with the Bruins against the Toronto Maple Leafs on Dec. 5, 2009. He finished with five goals and 15 points in 51 games. In 2010-11, he helped Boston win the Stanley Cup, scoring three goals, nine points and finishing with a plus-12 rating in 25 games.

After three more seasons with the Bruins, including another trip to the Stanley Cup Final in 2013, Boychuk was traded to the New York Islanders on Oct. 4, 2014. He scored 35 points (nine goals, 26 assists) in 72 games and signed a seven-year contract March 12, 2015.

The following season, Boychuk helped the Islanders advance to the second round of the playoffs for the first time since 1993; he scored 25 points (nine goals, 16 assists) in 70 regular-season games in 2015-16 and played in all 11 playoff games.

He again helped New York reach the second round of the playoffs in 2018-19, scoring 19 points (three goals, 16 assists) in 74 games.

However, Boychuk sustained an injury to his left eye in a game against the Montreal Canadiens on March 3, 2020, and needed 90 stiches to close a skate cut. He was able to return for the Islanders' first postseason game but sustained a concussion. Boychuk didn't play again until dressing for Games 5 and 6 of the Eastern Conference Final, but said on Nov. 25, 2020, that he was ending his playing career because of the damage from the eye injury.

NOTES & TRANSACTIONS

• AHL First All-Star Team (2009)
• Eddie Shore Award (AHL -- Outstanding Defenseman) (2009)
• Traded to Boston by Colorado for Matt Hendricks, June 24, 2008.
• Signed as a free agent by Salzburg (Austria), November 16, 2012.
• Traded to NY Islanders by Boston for Philadelphia's 2nd round pick (previously acquired, Boston selected Brandon Carlo) in 2015 NHL Draft and NY Islanders' 2nd round pick (Ryan Lindgren) in 2016 NHL Draft, October 4, 2014.
• Traded to Buffalo by NY Islanders for future considerations, November 4, 2021.