Manufacturers have been under increasing pressure from various groups to recognize and deal with the environmental effects of their operations, especially in the past twenty years. To manage this challenge, they have adopted two practices: corporate social responsibility (CSR) and total quality management (TQM). However, it is still not clear how these practices are supposed to affect environmental performance in developing countries, particularly the less developed ones. This study aimed to fill this gap by researching whether TQM could mediate between CSR and green management in Iranian manufacturing companies. The Baron and Kenny method was used to achieve the answer. The structural equation modeling method, using AMOS, was additionally used to explore the relationships between the concepts. Out of 849 questionnaires distributed, 328 usable responses were received. The findings supported all hypotheses: CSR is linked to a company’s environmental performance, CSR is connected to TQM, TQM is associated with the company’s environmental performance, and the relationship between CSR and environmental performance is partly mediated by TQM. Practically, the findings of this study provide organizations with actionable guidance to enhance their environmental sustainability practices, resulting in fostering long-term sustainability and gaining a competitive advantage.