Recent organizational trends give more importance to the social and responsible behavior of organizations to their sustainability. Numerous factors are responsible for prioritizing social responsiveness and pro-environmental or employee-green behavior for organizational sustainability. Nevertheless, no studies have yet considered how voluntary green behavior (VGB) and socially responsible human resource management (SRHRM) influence this perception. Hence, this study determines the explanatory link of VGB along with the impacts of SRHRM on organizational sustainability (environmental [EnS], social [SS], and economic [ES] sustainability). Data was collected from a developing nation context. An explanatory research strategy was used for the present study. To acquire data from 100 Bangladeshi pharmaceutical manufacturing organizations, structured questionnaires were used. For testing the proposed hypotheses of the study, we used partial least squares structural equation modeling (PLS-SEM). The outcomes of the analysis reveal that SRHRM has a considerable impact, both positively and significantly, on organizational sustainability (EnS, SS, and ES). Once again, SRHRM has a substantial positive effect on VGB. Furthermore, VGB plays an influential role as a mediator in the relationship between SRHRM and organizational sustainability. The findings have significant implications for pharmaceutical manufacturing organization management in Bangladesh and other Southeast Asian contexts. Based on the findings, pharmaceutical company managers will have a stronger rationale to invest in SRHRM while simultaneously establishing strong ties with employees and CSR-oriented green behavior to accomplish their organizational sustainability objectives. This study contributes to the existing body of research on the sustainability of organizations and the triple bottom line, along with SRHRM and VGB, by providing evidence from a country that is rapidly industrializing and developing. In this work, SRHRM was measured as a whole, even though it has three dimensions. Since the sample consists of Bangladeshi pharmaceutical manufacturing organizations, it is also uncertain whether the results can be generalized.