Seguin became the 410th player in NHL history to play 1,000 regular-season games when he skated 21:48 and went 6-of-12 on face-offs for the Dallas Stars in a 2-1 loss to the Tampa Bay Lightning at Benchmark International Arena in Tampa, Florida, on Oct. 30, 2025. He was the 270th forward to achiever the milestone, one of 39 active players to do so and the third player from the 2010 NHL Draft to reach 1,000 games (Jeff Skinner, Cam Fowler).

Seguin was moved from wing to center after being acquired by the Stars in a trade with the Boston Bruins on July 4, 2013. He scored at least 33 goals in each of his first three seasons with the Stars, establishing himself as one of the game's elite and fulfilling the promise the Bruins projected when they selected him with the No. 2 pick in the 2010 draft.

He jumped straight to the NHL and had had 22 points (11 goals, 11 assists) in 2010-11 despite averaging 12:13 of ice time during his rookie season. Seguin also contributed seven points (three goals, four assists) in 13 Stanley Cup Playoff games to help the Bruins win their first championship since 1972.

Seguin began to break out the next season, finishing with 67 points (29 goals, 38 assists) and a plus-34 rating that was second in the NHL. He followed that up by scoring 16 goals and finishing with 32 points during the lockout-shortened 2012-13 season. But after Seguin scored one goal on 70 shots during Boston's run to the 2013 Stanley Cup Final, the Bruins traded him to the Stars.

Seguin tied Joe Pavelski and Max Pacioretty for the NHL lead with three hat tricks in 2013-14, his first season with Dallas, and has continued to pile up the goals and points, scoring 40 goals in a season for the first time in 2017-18.

Seguin had 80 points (33 goals, 47 assists) in 2018-19 to become the first player in Stars/Minnesota North Stars history with at least 60 points in each of his first six seasons to play for the franchise and third with at least that many in six consecutive seasons. That season, he was one of three players in the NHL (Nicklas Backstrom, Sidney Crosby) to score at least 70 points in six straight seasons (2013-14 to 2018-19).

Seguin started the 2023 Stanley Cup Playoffs with four power-play goals in the Western Conference First Round, a Dallas/Minnesota North Stars record and 20 years since any player scored more on the power play in a single round (Doug Weight scored five for the St. Louis Blues in the 2003 conference quarterfinals).

A native of Brampton, Ontario, Seguin played his junior hockey with Plymouth in the Ontario Hockey League, where he scored 69 goals and had 173 points in 124 games.

Seguin also helped Canada finish first at the 2015 IIHF World Championship, where he led all scorers with nine goals.