Can a seller carve out a piece of real estate and keep it personally after the sale?

Yes, this is a common seller preference, often for ongoing rental income or estate planning reasons. If the real estate currently sits inside the operating corporation, the seller generally transfers it out to themselves or another entity before the sale closes, so it's no longer part of what you're buying; if it was already held personally or separately, it simply isn't included in the sale to begin with.

The nuance that matters to you as buyer is what happens to the business's use of that property afterward. If the business needs to keep operating from that location, a new lease between you and the seller, as the property's new personal owner, needs to be negotiated and signed as part of the deal — its term, rent, and renewal rights matter as much as the purchase price itself, since you're now dependent on a landlord who used to be your seller. Under Ontario's Commercial Tenancies Act, a lease's consent-to-assign clause is generally deemed reasonable unless the lease says otherwise, but that's a separate question from negotiating fair terms on a brand-new lease.

A business lawyer negotiating both the carve-out and the resulting lease at the same time, rather than treating the lease as an afterthought, protects your ongoing use of the premises.