The No. 3 pick of the 2016 NHL Draft, Dubois set Blue Jackets rookie records for goals (20), points (48) and games played (82) in 2017-18, which included a goal in his debut against the New York Islanders on Oct. 6, 2017.

He took another step in 2018-19, surpassing previous totals with 61 points (27 goals, 34 assists). Dubois also helped the Blue Jackets win a Stanley Cup Playoff series for the first time, a sweep of the Tampa Bay Lightning in the Eastern Conference First Round. He scored five points (two goals, three assists) in 10 playoff games. On July 25, 2022, Dubois signed a one-year, $6 million contract with the Winnipeg Jets as a restricted free agent, six months after he was acquired in a trade with the Blue Jackets. His 36 assists and 63 points in 2022-23 were NHL career highs.

Dubois was traded to the Los Angeles Kings by the Jets on June 27, 2023, for Gabriel Vilardi, Alex Iafallo, Rasmus Kupari and a second-round pick in the 2024 NHL Draft. He signed an eight-year, $68 million contract with an average annual value of $8.5 million, and was traded to the Washington Capitals for Darcy Kuemper on June 19, 2024.

Dubois' father, Eric, was a fourth-round pick (No. 76) by the Quebec Nordiques at the 1989 NHL Draft.