A fire alarm alerted the occupants of the building on Paisley Boulevard at approximately 10:10 a.m., who called emergency services.
Firetrucks soon arrived at the scene where firefighters rushed to the smoke-filled hallway on the second floor.
The thick, black, billowing smoke was caused by a fire that broke out in a bedroom in one of the units.
According to Alan Hills, a platoon chief for Mississauga Fire and Emergency Services, the crew "quickly brought the fire under control."
The smoke migrated to the adjacent units as well as the upper levels of the building.
"Working smoke alarms save lives," said Hills. "In this case it's important to note that the occupants were notified because the alarm system was working properly."
Firefighters evacuated the entire building and sheltered the occupants on public transit buses.
According to officials, there were no deaths or injuries and no cause has been determined.
Officials estimate that the smoke and fire damage may amount to $100,000.