This study examines the effects of transformational and transactional leadership behaviors on relationship commitment in the supplier–buyer–user supply chain. The focus is on the activities and relationships between (1) the corporate buyers and the internal users and (2) the corporate buyers and the external suppliers in the supply chain. To assess the relationships in the supplier–buyer–user supply chain, two different samples are used to test the developed framework: (1) a user sample consisting of 346 strategic business unit users of a major multinational corporation and (2) a buyer sample consisting of the corporate buyers of 200 National Association of Purchasing Management member corporations. Overall, the results suggest that transformational leadership behaviors have a positive influence on building commitment in the dyadic relationships between (1) users and buyers and (2) buyers and suppliers. As such, transformational leadership affects the quality of the supply chain relationship among the interdependent units that form a long-linked partnership to serve customers.