As a freshman at Boston College in 2019-20, Newhook earned the Tim Taylor Award as the NCAA Division-I Rookie of the Year, the first player from the school to do so. He was also named the Hockey East Rookie of the Year, the ninth player in program history to be recognized as the league's top first-year player. Newhook tallied 42 points (19g/23a) and ranked ninth nationally in points per game and tied for the team lead in scoring. He led all NCAA freshmen in goals, game-winning goals (4) and short-handed goals (3), while his +28 rating was third in the country.
Selected by the Avalanche in the first round (16th overall) of the 2019 NHL Draft, Newhook spent two seasons with the Victoria Grizzlies of the British Columbia Hockey League from 2017-2019, producing 168 points (60g/108a) in 98 career regular-season games and 33 points (14g/19a) in 27 total postseason contests. He served as team captain in 2018-19 and led the league with 102 points (38g/64a), pacing the BCHL in assists and finishing third in goals to earn the Vern Dye Memorial Trophy as the league's most valuable player and be named a BCHL First Team All-Star. Newhook added a league-leading 24 points (11g/13a) in 15 postseason games, ranking second in goals and tied for fourth in assists.
In 2017-18, Newhook ranked first among BCHL rookies with 66 points (22g/44a) and was tops among first-year players in assists and second in goals. The 5-foot-10, 190-pound center won the Bruce Allison Memorial Trophy as the league's rookie of the year and was named a BCHL First-Team All-Star. He notched nine points (3g/6a) in 12 playoff outings.
Newhook also represented his country at the 2019 IIHF U18 Men's World Championship in Sweden, registering 10 points (5g/5a) in seven tournament contests to tie for the team lead in points. He suited up for Team Canada Black at the 2017 World Under-17 Hockey Challenge, finishing with four points (1g/3a) in five outings.
