Corporate social responsibility (CSR) has emerged as an imperative for every sector globally. Yet, for a long time, the concept of CSR has been regarded from an organizational perspective. However, the importance of CSR in shaping the extra-role behavior of employees, such as their pro-environmental behavior (PEB-E), has been under-explored in the literature. Against this backdrop, the current study aims to investigate the impact of CSR on PEB-E with the mediating effect of work engagement (W.E) in the context of a emerging country. The study also employs stewardship theory as an alternate theory to explain the proposed relationships. The data of the current study were obtained from SME sector through a self-administered (paper-and-pencil method) questionnaire. A random sample of employees (n = 398) from different SMEs was selected and analyzed through structural equation modeling. The results of the current survey revealed that CSR directly and indirectly, via W.E, predicts PEB-E positively. The findings of the current study will be helpful for policymakers to understand that well-planned CSR activities, not only create positive repute for an SME, but also provide the underlying justification to its employees to be engaged in different environment-specific behaviors.