Can I sue a neighbour if I am injured on their property in Ontario?

Yes. A neighbour, like any other occupier, owes visitors to their property a duty under the Occupiers' Liability Act to take reasonable care to keep the premises reasonably safe, and can be liable if a hazard they knew or should have known about caused your injury - a broken step, an aggressive pet, an unsafe structure, or ice left untreated on a walkway. This uses the same general framework applied to any occupier, whether the property is residential or commercial.

That said, what counts as reasonable care for a private residential property can differ somewhat from what is expected of a business, since a homeowner is not necessarily held to the same systematic inspection and documentation practices expected of a commercial property. The purpose of your visit, and whether you were invited for that purpose, can also affect the scope of the duty owed to you. As with other occupier claims, documenting the specific hazard, when it arose, and what the homeowner knew or was told about it beforehand is important evidence to gather as early as possible after the injury occurs.