He attended Brock University and graduated with a degree in Sports Management, and started his career by briefly acting as a player agent.

Dubas joined the Maple Leafs organization as an assistant general manager in 2014, and played a key role in developing the Toronto Marlies of the American Hockey League (AHL).

At the time of his hiring by the Maple Leafs, Dubas was the second youngest general manager in NHL history, behind John Chayka of the Arizona Coyotes.

[4] In 2014, Toronto Maple Leafs team president Brendan Shanahan reached out to Dubas about the possibility of joining the organization.

[8] 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.

[7] Dubas and Mark Hunter filled the role of interim general manager for the Maple Leafs in 2015, after Nonis was fired by the club.

[9] After Shanahan hired Lou Lamoriello to serve as the team's general manager, Dubas and Hunter both took roles as assistant GM.

[11] 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.

[24] However, his second season the team fell in the qualifying round at the hands of the Columbus Blue Jackets and failed to make the playoffs at all.

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.

"[27] 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.

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.

"[28] In December 2019, when Ilya Mikheyev suffered a laceration on his wrist and was removed from an away game with the New Jersey Devils and had to undergo surgery at University Hospital in Newark,[29] Dubas and assistant athletic trainer Jon Geller cleared their schedules so Mikheyev would have familiar people around in the three days between his surgery and flying back to Toronto.

[31] Dubas was hired as President of Hockey Operations for the Pittsburgh Penguins on June 1, 2023,[32] replacing Brian Burke, and subsequently assuming the role of interim general manager.

[34] During his time with the Greyhounds in the OHL, Dubas believed that data could provide a way for smaller teams to close the gap with the league's traditional powerhouse programs.