Jersey Devils, just a little over a year from when he was acquired on February 29, 2016, in exchange for Stefan Matteau. During the offseason, on July 1, 2016, Smith-Pelly signed a two-year, $2.6 million contract extension with the Devils. 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. On July 3, 2017, he was signed to a one-year, two-way contract with the Washington Capitals with a $650,000 salary. On February 17, 2018, Smith-Pelly was the target of a racist chant by four fans at the United Center during a game against the Chicago Blackhawks. The four fans, who were chanting the word "basketball", were escorted out of the United Center and issued a lifetime ban from the arena by the Blackhawks organization. Both the NHL and Blackhawks condemned the action of the four fans and apologized to Smith-Pelly. Smith-Pelly scored seven goals in the 2018 playoffs, including the tying goal in the clinching game five of the Stanley Cup, helping the Capitals secure their first NHL title in team history. Smith-Pelly became the second player in NHL history, behind Patrice Bergeron-Cleary to have a hyphenated surname engraved on the Stanley Cup. During the 2018–19 season, Smith-Pelly continued with the Capitals in a fourth-line role. 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 on 21 February. He was then assigned to affiliate, the Hershey Bears, returning to the AHL for the first time since 2014. Smith-Pelly returned to the Washington Capitals during the 2019 Stanley Cup first-round series after T. J. Oshie was injured in Game 4 versus the Carolina Hurricanes. 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. In the 2019–20 season, Smith-Pelly in a checking-line role added 8 goals and 11 points through 36 regular season games. In the pandemic delayed 2020–21 season, Smith-Pelly belatedly returned to the North American professional circuit after accepting a professional tryout contract with the Ontario Reign of the AHL, primary affiliate to the Los Angeles Kings