Fox, 21, skated in 33 games with Harvard University this past season, registering nine goals and 39 assists for 48 points, along with a plus-23 rating and 14 penalty minutes. He was named a finalist for the Hobey Baker Award as the top player in collegiate hockey in 2018-19, and he was also named a First Team All-American. Fox established collegiate career-highs in several categories during this past season, including goals, assists, points, and plus/minus rating. He led the NCAA in assists and ranked fourth in the NCAA in points in 2018-19; he ranked second among NCAA defensemen in points, only trailing Hobey Baker Award winner Cale Makar (49). In addition, Fox led the NCAA in assists per game (1.18) and points per game (1.45) during the past season. He led all players in ECAC Hockey in overall points, as well as in points in ECAC Hockey conference games (33 points in 22 intra-conference games) in 2018-19.

The 5-11, 195-pounder has skated in 97 career collegiate games over three seasons (2016-17 – 2018-19) with Harvard, registering 21 goals and 95 assists for 116 points, along with a plus-45 rating and 32 penalty minutes. Fox has led NCAA defensemen in assists and points since he began his collegiate career, and he has registered 17 more points and 19 more assists than any other NCAA defenseman over the span. In addition, Fox leads all NCAA players in assists since he began his collegiate career. Over the last 20 seasons (since 1999-00), he has averaged more points per game than any other NCAA defenseman (1.20). Fox has been named a First Team All-American in each of his three collegiate seasons. He led all NCAA defensemen in points as a freshman in 2016-17 (40), and he was named the ECAC Hockey Rookie of the Year. In addition, Fox helped Harvard win the ECAC Hockey Championship and advance to the Frozen Four in 2016-17, and he was also named to the ECAC Hockey All-Tournament Team in 2016-17.

Internationally, the Jericho, New York native has represented the United States in four major tournaments, and he has helped Team USA earn a medal in all four of them. Most recently, Fox helped the United States earn a bronze medal at the 2018 IIHF World Junior Championship, as he registered five points (one goal, four assists) and a plus-six rating while serving as one of the team’s alternate captains, and he was named one of the Top Three Players on his Team in the tournament. He also helped the United States earn a gold medal at the 2017 IIHF World Junior Championship, as he notched four assists in seven games. Fox was named the Best Defenseman at the 2016 IIHF U18 World Championship while helping the United States earn a bronze medal, as he registered nine points (one goal, eight assists) and a plus-15 rating in seven games and led all defensemen in the tournament in assists and points. In addition, he earned a silver medal with the United States at the 2014 World U17 Hockey Challenge.

Fox was originally selected by Calgary in the third round, 66th overall, of the 2016 NHL Entry Draft. He was acquired by Carolina in a trade with Calgary on June 23, 2018.