Scandella began his junior career with the Val d'Or Foreurs of the QMJHL. Shortly after returning from the 2010 World Junior Championships tournament, Scandella was suspended for 15 games by the QMJHL for elbowing Alexandre Durette of the Rimouski Océanic in the head.
Professional
Minnesota Wild
Scandella made his NHL debut for the Minnesota Wild on November 12, 2010, against the Florida Panthers. He scored his first career NHL goal during the first game of the 2011–12 season against Steve Mason of the Columbus Blue Jackets. Scandella began his breakout year in the 2013–14 season, skating in 76 games with the Wild and playing the majority of his minutes on the second defensive pairing with close friendJared Spurgeon. He scored three goals and added 14 assists for 17 points over the course of the season. There were high expectations for Scandella entering the 2014–15 season. He immediately made an impact, going on a scoring streak and surpassing his career totals of goals scored. He scored the overtime winners against the Winnipeg Jets and Dallas Stars on November 14 and November 29, and on the latter date signed a five-year, $20 million contract extension with Minnesota. Scandella was later fined $2,755.38 for an illegal check to the head of the St. Louis Blues' T. J. Oshie on December 1, and nine days later, he was suspended a further two games for the same infraction against the New York Islanders' Brock Nelson.
Buffalo Sabres
After seven seasons with Minnesota, Scandella was traded to the Buffalo Sabres on June 30, 2017 in exchange for Tyler Ennis, Marcus Foligno and a third-round pick.
Montreal Canadiens
Entering the final year of his contract in the 2019–20 season, Scandella contributed with three goals and nine points in 31 games. On January 3, 2020, Scandella was traded to the Montreal Canadiens in exchange for a 2020 fourth-round pick. He scored his first goal for the Canadiens on February 8 in a 2-1 overtime win against the Toronto Maple Leafs.
St. Louis Blues
On February 18, 2020, Scandella, after only one month with the Canadiens, was traded on to the St. Louis Blues in exchange for a 2020 second-round pick and 2021 conditional fourth-round pick. Scandella made 11 regular season appearances with the Blues, registering 1 assist, before the season was suspended due to COVID-19]. On April 16, 2020, the Blues signed Scandella as an impending free agent to a four-year, $13.1 million contract extension.
