Can a landlord demand my buyer sign a personal guarantee even if I never had to give one?

Generally yes, if the lease's consent provision gives the landlord room to set conditions on approving a new tenant. A landlord's willingness to consent to an assignment is often treated as a fresh opportunity to reassess risk, and a personal guarantee from the incoming tenant's principals is a common condition — even where the original tenant never had to provide one, particularly if the landlord views the buyer's financial standing as weaker or simply prefers the extra security a guarantee provides.

Whether this demand is enforceable against your buyer, or challengeable as an unreasonable condition, depends on your lease's specific consent wording and the reasonableness standard it incorporates, if any. A demand tied to a genuine concern about the buyer's covenant strength is generally on firmer ground than one that looks arbitrary or unrelated to any real risk.

Your buyer isn't necessarily obligated to accept — this becomes a negotiating point in the deal, and sometimes an issue that affects price or deal structure. A Treadstone business lawyer can assess whether the demand is reasonable and help your buyer negotiate its scope.