The lights went out for about 40 minutes at around 7 a.m., affecting operations in the domestic terminal which handles flights within Canada.
Although power was restored as quickly as possible, it took longer to bring numerous computer systems back online.
Officials with the airport said that caused some delays, especially for passengers trying to check-in or make their way through security screenings.
All systems were back up and running normally by mid-morning and any backlogs had been cleared.
The cause of the outage is under investigation.