Following the end of the 2017 U Sports football season, Cranston re-signed with the Alouettes to a three-year contract on March 14, 2018.

[5] Cranston began the 2018 Montreal Alouettes season on the suspended list before moving to the practice roster.

[6] He then made his regular season professional debut on September 30, 2018, against the Saskatchewan Roughriders where he had one special teams tackle.

[7] In 2019, Cranston made the team's opening day roster where he recorded his first defensive tackle against the Edmonton Eskimos on June 14, 2019.

[8] Due to the cancellation of the 2020 CFL season caused by the COVID-19 pandemic in Canada, Cranston did not play that year.