[7] During his 20 games with the Juniors, Hintz tallied 20 goals and 15 assists for 35 points as he got acclimated to the smaller ice surfaces in North America.

[16] Following the conclusion of the 2016–17 Liiga season, Hintz signed a three-year, entry-level contract with the Dallas Stars.

[27] Following their Calder Cup loss, Hintz participated for the Stars in the 2018 NHL Prospect Tournament in Traverse City, Michigan.

During the tournament, he centered the Stars' top line with various linemates including Nick Caamano and Jason Robertson.

[28] He continued to impress the Stars' coaching staff during their preseason games and spent time centering the top line with Jamie Benn and Alexander Radulov.

[29] As a result of his impressive training camp and preseason efforts, Hintz was named to the Dallas Stars roster to start the 2018–19 NHL season.

[30] He subsequently made his NHL debut on 4 October 2018, playing 9:59 and recording one shot on goal and four hits in a 3–0 win over the Arizona Coyotes.

[33] Upon returning to the AHL, Hintz earned a spot on their top line alongside Denis Gurianov and Michael Mersch as he recorded four points through his first three games.

By February, Hintz began to earn top-six minutes while playing on the left wing with Tyler Seguin and Alexander Radulov.

[40] Beyond improving in faceoffs, Hintz also scored his first and second career playoff goals on 17 April 2019 to even up the series against the Predators.

[44] Throughout the month of October, he centered the top line with Jamie Benn and Corey Perry while leading the team in points and goals.

[45] His strong start to the season was cut short in November after he suffered a lower body injury during a game against the Montreal Canadiens.

[52] When the NHL paused play due to the COVID-19 pandemic, Hintz was tied with Benn for second on the team with 19 goals despite ranking eighth among its forwards in average ice time per game.

[53] When the NHL resumed playing in August, Hintz and the Stars defeated the Calgary Flames, Colorado Avalanche, and Vegas Golden Knights to qualify for the Stanley Cup Finals.

[54] The Stars eventually defeated the Flames in the six games to face off against the Colorado Avalanche in the Western Conference Second Round.

[55] During game 1 of their series against the Avalanche, Hintz tallied his first postseason goal of the tournament to lead the Stars to a 5–3 victory.

[56] He eventually helped the Stars defeat the Avalanche in seven games to face the Vegas Golden Knights in the Western Conference Final.

[59] Following the Stars' elimination from the playoffs, Jim Nill signed Hintz to a three-year contract extension worth $9,450,000 with an average annual value of $3,150,000.

[60] During the off-season, Hintz took four weeks off to rest and recover in Finland but underwent an MRI upon his return to Dallas that revealed surgery was required.