The current study aimed at exploring the impact of supply chain internal and external integration on the operational performance of manufacturing companies operating in Jordan, as well as addressing the possibility of a mediation effect of lean operations and practises on the proposed relationship. Achieving the study objectives necessitated using the deductive approach and the descriptive survey approach. Using a well-designed questionnaire, the primary data was collected from a 315-manager sample randomly selected from the companies. Accordingly, the nature of how supply chain integration, lean operations, and operational performance impact each other was investigated. The study results revealed that integrating the supply chain both internally and externally could increase the opportunity to attain a more desirable operational performance, particularly in terms of quality performance measures. Moreover, in the vein of adopting lean practices among manufacturing companies, a positive mediation effect was found. Thus. In light of these results, it is concluded that lean operations, as a mediating variable, positively influence the association between internal and external supply chain integration on quality measures of operational performance.