Can a tenant claim ownership of a rented property after living there for years?

Generally, no — a tenant occupying property with the landlord's permission (i.e., paying rent under a valid tenancy) cannot claim ownership through adverse possession, since adverse possession specifically requires occupation that is hostile and without the owner's permission, which is the opposite of a permissive tenancy relationship.

As long as the tenant continues to acknowledge the landlord's ownership — by paying rent, for instance — length of tenancy alone, even a very long one, doesn't convert into an ownership claim.

That said, complications can arise if the tenant stops paying rent for an extended period and starts asserting ownership openly, without the landlord objecting or taking action — this could, in unusual and fact-specific circumstances, potentially support an adverse possession claim if it continues long enough and meets all the legal requirements. To stay safe, it's advisable to maintain a proper, documented tenancy relationship (rent receipts, a written agreement) and act promptly if the tenant's conduct changes.