Early years As a youth, Newhook left his native
Newfoundland to play hockey for
St. Andrew's College, a
boarding school located in
Aurora, Ontario. Thereafter, he joined the York Simcoe Express of the
Eastern AAA Hockey League (ETAHL) where he served as
team captain and was named as the
U16 AAA Player of the Year across the
Ontario Minor Hockey Association (OMHA) in 2017.
Junior Newhook joined the
Victoria Grizzlies of the
British Columbia Hockey League (BCHL) for the
2017–18 season where he finished second in team scoring with 66 points in 45 games played. He also recorded nine points through 12
postseason games and was named as team captain thereafter. Early into the
2018–19 season, Newhook signed his
Letter of Intent to join
Boston College of the
National Collegiate Athletic Association (NCAA) beginning in the
2019–20 NCAA season. After leading all BCHL skaters in scoring during his final year, he earned the Vern Dye Memorial Award as the league's
most valuable player (MVP). Similarly, he was also recognized as the MVP across the
Canadian Junior Hockey League (CJHL). Following the season, Newhook was selected in the first round, 16th overall, by the
Colorado Avalanche in the
2019 NHL entry draft.
Collegiate Newhook had an impressive
freshman campaign with the
Boston College Eagles, posting 19 goals and 23 assists for 42 points in 34 games. Collectively, he led all
Hockey East freshmen in points and goals, all NCAA freshman in goals, and tied for seventh in scoring among all NCAA skaters. For his efforts, Newhook was named recipient of the
Tim Taylor Award, becoming the first such player in Boston College history, as well as the Hockey East Rookie of the Year. He likewise earned Hockey East Second Team All-Star honors and would be named to the conference All-Rookie Team. Due to participation in the
2021 World Juniors tournament and underlying
quarantine requirements prior thereto, Newhook missed the start of his
sophomore campaign at Boston College. After returning to campus following a silver medal result with
Team Canada, he was injured in his Eagles season debut. Collectively, Newhook would be limited to just 12 games over the course of the
2020–21 season, posting a total seven goals and 16 points. After producing at the AHL level, collecting five goals and nine points through eight games played, Newhook was called up to the Avalanche's
taxi squad on May 2, 2021. He made his NHL debut three days later in a 3–2 loss to the
San Jose Sharks. Appearing in six total games with the Avalanche during the
2020–21 season, he scored his first NHL goal in the ensuing
Stanley Cup playoffs during Game 3 of the team's opening round series against the
St. Louis Blues on May 21. He ultimately skated in eight playoff games before Colorado was ousted in the second round by the
Vegas Golden Knights. Securing an opening night roster spot ahead of the
2021–22 season, team head coach
Jared Bednar would reassign Newhook to the Eagles after a single game, citing his need for "more confidence with the puck." Returning to the NHL ranks after ten games, he would register 33 points over the remainder of the regular season. After sporadic use in both the Avalanche's first and second round series against the
Nashville Predators and St. Louis Blues respectively, Newhook then played the entirety of the
Western Conference Final against the
Edmonton Oilers and championship-clinching
Stanley Cup Finals over the
Tampa Bay Lightning, contributing four assists in 12 total games. With the victory, he effectively became the third player from Newfoundland and Labrador to win the
Stanley Cup, following
Daniel Cleary (
2008) and
Michael Ryder (
2011). The
2022–23 season was poised at the outset to be a significant opportunity for Newhook, as the departure of longtime second line centreman
Nazem Kadri left a positional vacancy that the team would give him the opportunity to fill. He soon experienced difficulties in this endeavour, not aided by an array of injuries to other Avalanche players, and was soon supplanted by
J.T. Compher. As well, coach Bednar frequently preferred to play him as winger. On December 5, Newhook skated in his 100th career NHL game, a 5–3 loss to the
Philadelphia Flyers, scoring a goal. He finished the regular season with 14 goals and 16 assists in 82 games. By season's end, it was widely assessed that he had not been able to take the next step the team had been hoping he would, raising questions as to his future with the team. The trade reunited him with his former agent,
Kent Hughes, with the foregoing now serving as the Canadiens' general manager. On July 11, 2023, Newhook was re-signed by the Canadiens to a four-year, $11.6 million contract extension. Newhook played his first game with the Canadiens on October 11, 2023, scoring two goals in the team's season opener. Initially, he had been placed on the team's second line with
Kirby Dach and
Juraj Slafkovský, a pairing that received strong initial assessments prior to the former sustaining a long-term injury in only the team's second game of the
2023–24 season. As a result, head coach
Martin St. Louis announced that Newhook would be shifted back to the centre position to replace Dach. After struggling at the centre position, Newhook would be placed back to the wing following
Christian Dvorak's return to the lineup in early November. Enjoying more success in that role, he registered seven goals and six assists, ranking fourth on the team in points, before sustaining a
high ankle sprain in a November 30 game against the
Florida Panthers which resulted in a prolonged absence. Newhook would ultimately return after missing a total of 27 games on February 10, 2024 versus the
Dallas Stars. He then reached a series of career milestones over the remainder of the campaign. On March 19, he skated in his 200th career NHL game in a 3–2
overtime loss to the Edmonton Oilers whereas he recorded his 100th career NHL point on April 16 against the
Detroit Red Wings. In the early stages of the
2025–26 season, Newhook collected 12 points (six goals, six assists) through 17 games before fracturing his ankle after hitting the boards feet-first during a matchup versus the Dallas Stars on November 13. Following surgery to repair same, he was expected to miss four months of action. ==International play==