Environmental issues are becoming major concerns for many supply chain management practitioners. Product disposal regulations have also led to firms adopting sustainable supply chain practices. This study assessed the effect of sustainable supply chain practices on organizational performance with firm competition serving as a mediating factor from an emerging economy perceptive using the institutional theory and the ecological modernization theory as underpinning theories. Data from195 firms were employed and analysed using SPSS (v.25) and the Hayes Macro Process. The results established green packing as the most practiced sustainable supply chain practice in Ghana. Green manufacturing has a positive effect on the environmental performance and the operations performance of manufacturing firms. Green purchasing was also identified to have a positive impact on the environmental but not on the operations performance of manufacturing firms. Green packaging also, has a positive impact on both the environmental performance of manufacturing firms and their operations performance. Furthermore, the result of the study concluded that reverse logistics do not positively influence environmental performance but positively influence the operations performance of manufacturing firms. Firm competition was identified to mediate the relationship between sustainable supply chain practices and organizational performance of manufacturing firms.