Duclair parlayed a three-year contract he signed with the Florida Panthers on July 15, 2021 into the first 30-goal season of his NHL career April 13, 2022. He earned the new deal after playing the 2020-21 season for Florida, where he signed a one-year contract Dec. 17, 2020, coming off his previous NHL career high 23 goals for the Ottawa Senators, where he capitalized on the chance to play top-six minutes after being acquired in a trade with the Columbus Blue Jackets on Feb. 23, 2019. He scored eight goals in 21 games after coming to Ottawa in 2018-19, then had 21 in his first 47 games in 2019-20, earning a trip to the 2020 NHL All-Star Game.

The Senators were the fifth NHL team in the Pointe-Claire, Quebec, native's career -- before he turned 24.He found a home in South Florida after negotiating his own one-year contract and had nine points (two goals, seven assists) in 20 games coming off Achilles tendon surgery July 2, 2022, to help the Panthers reach the 2023 Stanley Cup Final.

Duclair was traded to the San Jose Sharks on July 1, 2023, for forward Steven Lorentz and a fifth-round pick in the 2025 NHL Draft. He was then sent to the Tampa Bay Lightning with a seventh-round pick in the 2025 NHL Draft on March 7, 2024, for defenseman prospect Jack Thompson and a third-round pick in the 2024 NHL Draft.

Duclair signed a four-year contract with the New York Islanders on July 1, 2024, reuniting him with Islanders coach Patrick Roy, his coach with Quebec of the Quebec Major Junior Hockey League. He had five points (three goals, two assists) in a 9-0 win against the New Jersey Devils at UBS Arena on Jan. 6, 2026, becoming the first with that many in one game since Mathew Barzal on April 1, 2021. He was on the ice for six of New York's nine goals for a plus-6 rating, the best by an Islanders skater since Bryan Trottier (plus-7) and Mike Bossy (plus-6) on Nov. 26, 1983.

After seeing the chemistry between Max Domi, their first-round pick in the 2013 NHL Draft, and Duclair, who had been selected by the New York Rangers in the third round (No. 80) while they were linemates for Canada at the 2015 IIHF World Junior Championship, the Arizona Coyotes jumped at the chance to acquire him in a trade with the Rangers.

On March 1, 2015, the Coyotes traded Keith Yandle, Chris Summers and a fourth-round pick in the 2016 NHL Draft to the Rangers for Duclair, John Moore, a second-round choice in the 2015 NHL Draft and a 2016 first-round pick.

Putting Duclair with Domi on the same line during the 2015-16 season paid off for Arizona. On Oct. 14, 2015, the duo combined for all the goals -- including Duclair's first NHL hat trick -- in a 4-0 win over the Anaheim Ducks. The hat trick was the first by a Coyotes rookie since Daniel Carcillo had one April 4, 2008 against the Dallas Stars.

Duclair finished the season with 20 goals and 44 points, which placed him fourth on the team in scoring. He and Domi combined for 96 points, and Duclair had two five-game point streaks during the season: one from Nov. 14-25, 2015 and another from March 22-31, 2016. He also had three multigoal games and eight multipoint games and scored the shootout-deciding goal Jan. 25, 2016, against the Minnesota Wild, the first shootout goal of his NHL career.

The Coyotes traded Duclair to the Chicago Blackhawks on Jan. 10, 2018, and he signed as a free agent with Columbus on July 6, 2018.

Duclair made the Rangers out of training camp in 2014-15 and had one goal, seven points and a plus-4 rating in 18 games. Duclair made his NHL debut Oct. 9, 2014, against the St. Louis Blues. His first NHL points came two nights later, when he had two assists against the Blue Jackets, and he scored his first NHL goal against the Minnesota Wild on Oct. 27, 2014.

Duclair played four seasons in the QMJHL. In 2013-14 he was third in the league with 50 goals and sixth with 99 points. Duclair also helped Canada finish first at the 2015 World Junior Championship, scoring four goals and finishing with eight points in seven games.