Can my buyer demand landlord consent as a condition before they'll pay me anything?

Yes, and this is one of the most standard and sensible protections a buyer can ask for in a business purchase and sale involving leased premises. If the business depends on operating from that specific location, a buyer who can't secure the lease has effectively lost the thing they're paying for — so making landlord consent to the assignment a condition of closing (and of releasing any deposit or purchase price) is a normal, well-accepted way to allocate that risk rather than an unreasonable demand.

How this actually plays out depends on your purchase agreement's drafting: whether consent is a condition of closing entirely, whether partial payment happens on signing with the balance tied to consent, and what happens if consent is delayed, refused, or comes with conditions neither party anticipated. These mechanics are negotiated, not automatic.

Because the timing and structure of payment tied to landlord consent affects your cash flow and certainty as a seller too, it's worth negotiating these terms carefully rather than accepting a buyer's first draft. A Treadstone business lawyer can help balance both sides' interests in the agreement.