The purpose of this paper is to explore the impact of supply chain flexibility on the competitiveness and firm performance and to explain the role of competitiveness as mediator for the relation between supply chain flexibility and firm performance. Methods of data Journal of Management Research ISSN 1941-899X 2013 www.macrothink.org/jmr 270 collection was survey. The sample was the manager of large-scale fishery firms in the Southeast Sulawesi. Research results showed the high supply chain flexibility has a significant effect on higher competitiveness, but does not has significant effect on firm performance, there for competitiveness has significant effect on firm performance. Finally, competitiveness becomes a complete mediation relationship between supply chain flexibility on firm performance. The practical implications of this study was to provide insight and knowledge to fishery firm managers, particularly in Southeast Sulawesi and Indonesia and generally in other developing countries, in implementing the concept supply chain flexibility by observing the capability of their partners in the supply chain to respond market changes in achieving and maintaining competitiveness and firm performance. Originality of this research was to provide the basis for an integrated configuration model in testing the relationship between supply chain flexibility on competitiveness and firm performance, and also on the role of competitiveness as mediator in improving firm performance.