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.