This research investigated the relationship between sustainable management practices and corporate environmental responsibility among deposit money banks operating in Delta State, Nigeria. Specifically, the study assessed the influence of green operational practices on corporate environmental responsibility and examined how the implementation of sustainability policies contributes to environmentally responsible corporate behaviour within the banking sector. A cross-sectional survey research design was adopted for the study. The target population comprised employees of selected deposit money banks in Delta State, from which a sample of 187 respondents was drawn using the Taro Yamane sample size determination formula. Data were obtained from primary sources through the administration of structured questionnaires. The quality of the instrument was established through face and content validity procedures, while its internal consistency was verified using Cronbach's Alpha, with all reliability coefficients exceeding the minimum acceptable benchmark of 0.70. Data analysis was conducted using descriptive statistics, Pearson Product Moment Correlation, and Multiple Regression Analysis with the aid of the Statistical Package for the Social Sciences (SPSS) Version 27. The empirical results indicated that green operational practices exert a significant positive influence on corporate environmental responsibility (β = 0.461, t = 7.934, p < 0.05). Similarly, sustainability policy implementation was found to have a statistically significant positive effect on corporate environmental responsibility (β = 0.398, t = 6.882, p < 0.05). Correlation analysis further revealed strong positive associations among the variables, with green operational practices exhibiting a correlation coefficient of r = 0.751 with corporate environmental responsibility, while sustainability policy implementation recorded r = 0.723. In addition, the regression model produced an adjusted coefficient of determination (Adjusted R²) of 0.653, indicating that sustainable management practices collectively accounted for 65.3% of the variation in corporate environmental responsibility among the selected deposit money banks. Based on these findings, the study concluded that the adoption of sustainable management practices plays a significant role in improving corporate environmental responsibility within the banking industry in Delta State. Consequently, it recommended that deposit money banks should strengthen the integration of environmentally friendly operational initiatives, including digital and paperless banking, energy-saving technologies, and effective waste management systems, to enhance environmental sustainability. Furthermore, bank management should develop, implement, and continuously monitor robust sustainability policies that encourage environmental stewardship, regulatory compliance, transparent sustainability reporting, and responsible corporate environmental practices across the sector.