In today's competitive markets, organizations must possess a high level of adaptability to gain a competitive edge. To explore the impact of a sustainable supply chain on sustainable competitive advantage, this study examined strategic flexibility and flexibility-productivity as mediating variables. The research focused specifically on the dairy industry in Fars province and involves industry experts from the domestic sector, selected through judgment sampling. Data was collected via a questionnaire, and Structural Equation Modeling (SEM) was employed for analysis. The findings of the study indicated that the economic, environmental, and social dimensions of supply chain sustainability have a significant influence on product flexibility. Additionally, these dimensions have a notable impact on strategic flexibility, except for the social dimension's effect on production flexibility. Furthermore, both production and strategic flexibility positively and significantly contribute to the achievement of sustainable competitive advantage. In conclusion, this research highlighted the importance of a sustainable supply chain in attaining sustainable competitive advantage. The economic, environmental, and social dimensions play a crucial role in enhancing both product and strategic flexibility. By embracing sustainable practices and fostering flexibility in production and strategy, organizations in the dairy industry can maintain a competitive advantage over time. Manuscript profile