Can a commercial tenant be liable as an occupier instead of the building owner in Ontario?

Yes. The Occupiers' Liability Act defines an occupier based on actual control over premises, not on legal ownership, so a commercial tenant running a store or restaurant, and controlling the space its customers actually use, can be the responsible occupier for injuries happening inside that leased space, even though the building owner holds title to the property as a whole. The building owner may still be separately responsible for structural elements, common areas, or shared systems - such as the roof, elevators, or shared hallways - that it retained control over under the terms of the lease.

Which party ultimately bears responsibility for a specific hazard usually comes down to how the lease agreement allocates maintenance duties, and which party actually had control over the area where the injury occurred at the relevant time. Because commercial leases frequently split maintenance responsibility in ways that are not obvious to a customer walking through the space, both the tenant and the landlord are often initially named in these claims until it becomes clear which one genuinely controlled the area involved.