While playing with the Mississauga Rebels of the Greater Toronto Hockey League, Hughes applied for exceptional status to be able to enter the Canadian Hockey League a year early. After his application was denied, he played his final year with the Toronto Marlboros, putting up 159 points. After completing his minor career with the Marlboros, Hughes was drafted eighth overall by the Mississauga Steelheads in the Ontario Hockey League, despite his commitment to the U.S. National Team Development Program. Hughes kept his commitment and played with the USNTDP for the 2017–18 season. Splitting his time between the U17 and U18 team, he put up 116 points, nearly beating Auston Matthews's record. At the conclusion of the 2017–18 season, Hughes was awarded the Dave Tyler Junior Player of the Year Award as the best American-born player in junior hockey. During the 2018–19 season, Hughes broke the NTDP all-time points record that was previously held by Clayton Keller. In a 12–4 win over the Green Bay Gamblers on March 15, 2019, he recorded five points to give him 190 overall. In the same game, teammate Cole Caufield broke the NTDP record for most goals. On June 21, 2019, at the 2019 NHL Entry Draft, Hughes was selected first overall by the New Jersey Devils. On July 12, Hughes signed a three-year entry level contract with the Devils. Hughes recorded his first career NHL point on October 17, in a game against the New York Rangers. In doing so, he became the third-youngest player in franchise history to record a point. Two days later, he recorded his first career NHL goal in a 1–0 win over the Vancouver Canucks.
International play
In the 2018 IIHF World U18 Championships Hughes was selected as the tournament MVP, named to the All-star team, and was chosen as the best forward of the tournament. He was also the best scorer of the tournament with 12 points in 7 games. On December 23, 2018, Hughes was selected to compete at the 2019 World Junior Ice Hockey Championships alongside his brother Quinn. Hughes missed three games of the tournament with an undisclosed injury but returned to the lineup in time to help Team USA beat the Czech Republic. He recorded an assist on Noah Cates's goal in his return. Hughes ended the tournament with four assists as Team USA lost to Team Finland in the gold medal match. He later competed at the 2019 IIHF World U18 Championships where he broke Alexander Ovechkin's goals scored record as Team USA won a bronze medal. On May 1, 2019, Hughes was named to the senior United States roster to compete at the 2019 IIHF World Championship alongside his brother. At the age of 17, Hughes became the youngest player to represent Team USA at an IIHF World Championship. On December 6, 2019, Hughes' NHL team, the New Jersey Devils, announced they would not release him to play for Team USA at the 2020 World Junior Ice Hockey Championships.
