PurposeThere is a dearth of empirical research examining the influence of various facets of sustainable banking on the environmental sustainability performance (SP) of banks in developing economies like Bangladesh. This study looks at how green banking practices (GBPs), green finance (GF) and corporate social responsibility (CSR) practices affect SP in both direct and indirect ways.Design/methodology/approachThe research framework of this study was designed based on legitimacy theory to examine the direct and indirect impacts of GBP on environmental SP through GF and CSR practices. Based on a structured questionnaire and convenience sampling, the data were collected from banking institutions to investigate the association among the study variables. Subsequently, the obtained data were evaluated using a well-established structural equation modeling (SEM) approach via SmartPls 4.0 software.FindingsThe empirical findings reveal that GBP has a significant direct impact on GF, CSR practices and the banks' SP. Further, the findings show that GF has a direct and significant impact on CSR practices and SP. Likewise, CSR practices have a direct and significant influence on the SP of banks. Additionally, among indirect effects, both CSR practices and GF mediate the association between GBP and SP, whereas GF also has an indirect effect on the relationship between GBP and CSR practices. Surprisingly, the findings demonstrate that CSR practices do not have an indirect effect on the association between GF and SP. Hence, the greater the bank's involvement in green banking activities, the greater the influence of green financing and CSR practices on environmental sustainability.Originality/valueThis study adds to the growing body of research in the areas of sustainable banking and environmental sustainability literature by evaluating the link between GBP, CSR practices, GF and SP. Besides, this is a ground-breaking study that examines both direct and indirect effects of different aspects of sustainable banking (GBP, GF and CSR practices) on the SP of the banking industry in an emerging country like Bangladesh. On the theoretical level, it adds to the application and expansion of legitimacy theory in the sphere of banking and finance. It provides new insights into the dynamics of green banking, GF and CSR practices within the framework of legitimacy theory. Hence, the current study offers significant suggestions to managers, academicians and researchers on how to advance the sustainability of the banking industry by adopting green banking, GF and CSR practices.