Systems and methods for cost-based fulfillment tie breaking are disclosed. In some embodiments, a method may include receiving an indication of an order for an item stocked in a plurality of fulfillment centers, where a difference between a cost of fulfilling the order with one of the plurality of fulfillment centers and a cost of fulfilling the order with another one of the plurality of fulfillment centers is within a specified amount. The method may also include selecting a given one of the plurality of fulfillment centers to fulfill the order based, at least in part, upon expected costs corresponding to inventory positions that would result from fulfilling the order with each of the plurality of fulfillment centers.