The Scarborough Health Network says six patients are infected in a unit at its general hospital in the east of the city.
A spokesperson for the health network said the unit has been closed to admissions in order to protect patients and staff.
Leigh Duncan says improved infection prevention and control measures are in place in the affected unit.
Scarborough joins a growing list of Toronto hospitals that have declared an official outbreak, defined as two healthcare-related COVID-19 cases within 14 days.
St. Michael’s Hospital, St. Joseph’s Health Center, Toronto Western Hospital and the Center for Addiction and Mental Health have also reported outbreaks among staff or patients.