Abstract: The purpose of this study is to examine and explain the effect of internal and external of supply chain integration on Supply Chain Flexibility (SCF) and competitive advantage. More specifically, this research aims to test and explain the role of SCF as mediator for the relation between supply chain integration and competitive advantage. Design of this research used is explanatory research approach. The data are collected through survey methods as cross-section using questionnaire. The unit of analysis is big-scale fishery companies. The respondents as sample are the managers of fishery companies. The 3 hypothesis are tested through a Partial Least Square analysis (PLS). Results show that internal and external supply chain integration can increase SCF and company’s competitive advantage, there for SCF has significant effect on competitive advantage. Furthermore, season factor is as control variable in this study model has negative and no significant effect on competitive advantage. Finally, SCF becomes a partial mediation relationship between supply chain integration and competitive advantage. The originality of this research was to provide the basis for an integrated configuration model in testing the relationship between internal and external of supply chain integration on SCF and competitive advantage and also on the role of SCF as mediator in improving competitive advantage.