[4] During his first full season in the NHL with the Ducks in 2014–15, having produced 17 points in 54 games, on February 24, 2015, he was traded to the Montreal Canadiens in exchange for Jiří Sekáč.

[7] After Smith-Pelly regressed in the 2016–17 season, he was placed on waivers by the Devils in order to buy out the remaining year and $1.3 million left on his contract on June 30, 2017.

[11] The four fans, who were chanting the word "basketball" repeatedly, were escorted out of the United Center and issued a lifetime ban from the arena by the Blackhawks organization.

Through inconsistent play and contributing with 8 points in 54 games, on February 20, 2019, Smith-Pelly was placed on waivers by the Washington Capitals before successfully clearing the following day.

Smith-Pelly returned to the Washington Capitals during the first-round series in the 2019 playoffs after T. J. Oshie was injured in Game 4 versus the Carolina Hurricanes.

[14] Leaving the Capitals as a free agent, Smith-Pelly, with limited NHL interest, opted to sign abroad for the first time in his career, agreeing to a one-year contract with Chinese-based club, HC Kunlun Red Star of the Kontinental Hockey League on October 25, 2019.

One of two players to be loaned from the NHL (Tampa Bay Lightning forward Brett Connolly was the other),[4] he was named an alternate captain for the team.

After winning the Stanley Cup with the Capitals in 2018, Smith-Pelly, along with two of his teammates, declined to visit the White House, an NHL tradition, because of Donald Trump's political rhetoric.