In 2014, Toronto Maple Leafs team president Brendan Shanahan reached out to Dubas about the possibility of joining the organization.
 Their initial meeting lasted nine hours.
 Dubas was hired by Shanahan as an assistant general manager for the Maple Leafs in July 2014.
 The Maple Leafs organization deflected concerns about his age at the time he was hired, with general manager Dave Nonis saying "...Age was never a factor.
It’s whether or not you can do the job, and it was clear to us quickly that he’s going to be good at it."
In January 2015, Forbes named Dubas amongst its 30 Under 30 brightest young stars in the sport industry.
As an assistant GM for the club, Dubas played parts in many aspects of the organization, including personnel management and analytics, through the team's research and development group.
Dubas and Mark Hunter filled the role of interim general manager for the Maple Leafs in 2015, after Nonis was fired by the club.

After Shanahan hired Lou Lamoriello to serve as the team's general manager, Dubas and Hunter both took roles as assistant GM.
During his time as assistant GM for the Maple Leafs, Dubas also served as general manager of the Toronto Marlies, the Maple Leafs' American Hockey League (AHL) affiliate team.
 He was instrumental in organizing a system that developed players for the Maple Leafs team, while also being competitive in their own league.
 Dubas hired former Greyhounds head coach Keefe to oversee the Marlies development.
In 2018, the Marlies captured the Calder Cup as the AHL champions.

After the 2017–18 season, Shanahan decided not to renew Lamoriello's contract as GM, sticking to his original plan to have a fixed term on his time in the position before he transitioned into an advisory role.
Dubas and his co-assistant GM Mark Hunter were considered top candidates for the position.
 On May 11, 2018, Dubas was named as the 17th general manager in the club's history.
 Shortly after Dubas was named GM, both Hunter and Lamoriello left the organization.
 One of Dubas's first tasks as GM of the Maple Leafs was the 2018 NHL Entry Draft.
 He traded the team's first round selection at 25th overall to the St. Louis Blues in exchange for their pick at 29th overall and an additional draft pick at 76th overall.
 The Leafs drafted Swedish defenceman Rasmus Sandin who played in the OHL for the Sault Ste.
Marie Greyhounds, Dubas's former team.
 During his first free agency period, Dubas made headlines by signing the top unrestricted free agent available, John Tavares to a seven-year contract.

Off the ice, Dubas hired Hayley Wickenheiser to serve as assistant director of player development.
 When hiring scouts, Dubas introduced a system of blinded reviews, where scouting reports by potential hires were submitted anonymously, to remove bias from the process.
 One of the highest scorers during this stage was Noelle Needham, who was hired as an amateur scout to cover the Midwest region of the United States.
 Dubas has expressed a belief that increasing the diversity of the Maple Leafs staff will result in improved performance, saying "Research shows the more diverse your organization, the better your decision-making and the better your operation in general.
If you’re only hiring white males – and I’m saying that as a white male – you’re probably leaving a lot of good people, in terms of where your organization can go and how it can think and how it can evolve and develop."
 During the 2018–19 season, Dubas received praise for the way he handled allegations that defenceman Morgan Rielly used a homophobic slur during a game.
 Rielly was cleared the following day after an investigation by the NHL.
 At a press conference, the following day, Dubas said "It’s incumbent on us in management to build an environment if someone were gay, or were questioning their sexual orientation, that they don’t feel that they have to come in here and be somebody that they’re not."
In 2014, Toronto Maple Leafs team president Brendan Shanahan reached out to Dubas about the possibility of joining the organization.  Their initial meeting lasted nine hours.  Dubas was hired by Shanahan as an assistant general manager for the Maple Leafs in July 2014.  The Maple Leafs organization deflected concerns about his age at the time he was hired, with general manager Dave Nonis saying "...Age was never a factor. It’s whether or not you can do the job, and it was clear to us quickly that he’s going to be good at it." In January 2015, Forbes named Dubas amongst its 30 Under 30 brightest young stars in the sport industry. As an assistant GM for the club, Dubas played parts in many aspects of the organization, including personnel management and analytics, through the team's research and development group. Dubas and Mark Hunter filled the role of interim general manager for the Maple Leafs in 2015, after Nonis was fired by the club. 
After Shanahan hired Lou Lamoriello to serve as the team's general manager, Dubas and Hunter both took roles as assistant GM. During his time as assistant GM for the Maple Leafs, Dubas also served as general manager of the Toronto Marlies, the Maple Leafs' American Hockey League (AHL) affiliate team.  He was instrumental in organizing a system that developed players for the Maple Leafs team, while also being competitive in their own league.  Dubas hired former Greyhounds head coach Keefe to oversee the Marlies development. In 2018, the Marlies captured the Calder Cup as the AHL champions.
After the 2017–18 season, Shanahan decided not to renew Lamoriello's contract as GM, sticking to his original plan to have a fixed term on his time in the position before he transitioned into an advisory role. Dubas and his co-assistant GM Mark Hunter were considered top candidates for the position.  On May 11, 2018, Dubas was named as the 17th general manager in the club's history.  Shortly after Dubas was named GM, both Hunter and Lamoriello left the organization.  One of Dubas's first tasks as GM of the Maple Leafs was the 2018 NHL Entry Draft.  He traded the team's first round selection at 25th overall to the St. Louis Blues in exchange for their pick at 29th overall and an additional draft pick at 76th overall.  The Leafs drafted Swedish defenceman Rasmus Sandin who played in the OHL for the Sault Ste. Marie Greyhounds, Dubas's former team.  During his first free agency period, Dubas made headlines by signing the top unrestricted free agent available, John Tavares to a seven-year contract.
Off the ice, Dubas hired Hayley Wickenheiser to serve as assistant director of player development.  When hiring scouts, Dubas introduced a system of blinded reviews, where scouting reports by potential hires were submitted anonymously, to remove bias from the process.  One of the highest scorers during this stage was Noelle Needham, who was hired as an amateur scout to cover the Midwest region of the United States.  Dubas has expressed a belief that increasing the diversity of the Maple Leafs staff will result in improved performance, saying "Research shows the more diverse your organization, the better your decision-making and the better your operation in general. If you’re only hiring white males – and I’m saying that as a white male – you’re probably leaving a lot of good people, in terms of where your organization can go and how it can think and how it can evolve and develop."  During the 2018–19 season, Dubas received praise for the way he handled allegations that defenceman Morgan Rielly used a homophobic slur during a game.  Rielly was cleared the following day after an investigation by the NHL.  At a press conference, the following day, Dubas said "It’s incumbent on us in management to build an environment if someone were gay, or were questioning their sexual orientation, that they don’t feel that they have to come in here and be somebody that they’re not."
Kyle Dubas