[2] On August 12, 2016, the Wildcats traded MacEwen to the Gatineau Olympiques in exchange for a fifth-round selection in the 2017 QMJHL entry draft.
[4] He later signed an amateur tryout contract with the Canucks American Hockey League (AHL) affiliate, the Utica Comets, on April 10, 2017.
After spending the first 13 games of the 2019–20 season with the Comets, MacEwen and Tyler Graovac were recalled to the NHL on November 13, with Jalen Chatfield sent down to the AHL in their place.
[17] By the time that the COVID-19 pandemic forced the indefinite suspension of the NHL and AHL seasons, MacEwen had five goals, six points, and 20 penalty minutes in 17 games for Vancouver.
[18] He also joined Vancouver for the 2020 Stanley Cup playoffs, appearing in six games for a team that defeated the defending champion St. Louis Blues before losing in the second round to the Vegas Golden Knights.
[20] He had difficulty settling into the 2020–21 season, as several injuries and an outbreak of COVID-19 among players and staff led to a constant rotation of skaters on the fourth line.
[23] On October 12, 2021, shortly before the start of the 2021–22 NHL season, the Canucks placed MacEwen on waivers in order to make room for Alex Chiasson, who was being signed to a one-year contract.
[25] After successfully acquiring his US work visa, MacEwen joined the Flyers on October 20, skating on the fourth line alongside Nate Thompson and former QMJHL teammate Nicolas Aubé-Kubel.
[28] Under new coach John Tortorella, MacEwen played effectively on the fourth line alongside Nicolas Deslauriers and Patrick Brown.
[29] On March 3, 2023, the Flyers traded MacEwen to the Los Angeles Kings in exchange for Brendan Lemieux and a fifth-round pick in the 2024 NHL entry draft.
[38] On February 12, 2024, MacEwen was placed on waivers again by the Senators in order to make room on the roster for Anton Forsberg who was returning from injury.
While being raised in Stratford, Prince Edward Island by parents Craig and Juliana, his family ran a berry farm.