 Continuing to play with Dexter, Donato made his junior debut with the South Shore Kings in the United States Premier Hockey League before finishing with the Omaha Lancers of the United States Hockey League, having committed to a collegiate career with Harvard University, in following his father's footsteps who was now the Crimson's head coach.Having led the Crimson as a junior in scoring through the 2017–18 season with 26 goals and 17 assists for 43 points in just 29 games, Donato opted to leave the college early and turn professional.He signed a three-year, entry-level contract with the Bruins on March 18, 2018.