[6] On December 7, 2008, when a replacement was needed for Pittsburgh defenseman Hal Gill, Lovejoy received his first call-up to the NHL.

[7] Lovejoy was named to the PlanetUSA squad for the 2009 AHL All-Star Classic, which was held January 25 and 26, 2009, at the DCU Center in Worcester, Massachusetts.

[8] On April 11, 2009, Lovejoy received the Second Team AHL All-Star Award, as well as being named the League's top defenseman.

[9][10] Lovejoy notched his first NHL point with an assist during a 6–5 Penguins victory over the Boston Bruins on November 14, 2009.

[10][11] Shortly after the beginning of the lockout-shortened 2012–13 season, on February 6, 2013, Lovejoy was traded by the Penguins to the Anaheim Ducks in exchange for a fifth-round draft pick in 2014.

[12] Prior to the beginning of 2013–14 season, Lovejoy, as an unrestricted free agent, re-signed with the Ducks on a three-year contract.

[16] In the final year of his contract with the Devils in the 2018–19 season, Lovejoy appeared in 51 games from the blueline adding 7 points while leading the team in shorthanded icetime.

With the Devils out of playoff contention, on February 23, 2019, he was traded to the Dallas Stars in exchange for Connor Carrick and a third-round draft pick in 2019.

His father played hockey for Colby College, and his mother was a two-time All-American and all-time leading-scorer in lacrosse at UMass.

[21] On December 7, 2017, Lovejoy announced he would be donating his brain to concussion research, becoming the first active NHL player to do so.