This study examined the relationship between environmental protection and sustainable corporate social responsibility within Equity Bank Limited. The study was guided by the need to understand how environmental management practices influence CSR sustainability outcomes in the banking sector. A descriptive correlational case study design was adopted. Data were collected from 212 valid responses drawn from a sample of 250 employees across selected branches in Busia and Kakamega Counties. The study applied structured questionnaires measured on a five-point Likert scale, supported by pilot testing to improve reliability and validity. Data analysis involved descriptive statistics, Pearson correlation, and simple linear regression using SPSS version 28. The findings revealed that environmental protection practices are positively perceived among employees, with an aggregate mean score of 3.74. Correlation analysis indicated a moderate positive relationship between environmental protection and corporate sustainability (r = 0.478, p < 0.01). Regression results showed that environmental protection significantly predicted corporate sustainability (β = 0.478, p < 0.001), explaining 22.8% of the variation in sustainable CSR outcomes. The study concludes that environmental protection plays a significant role in strengthening sustainable CSR performance in banking institutions. It recommends enhanced promotion of green financing products, expanded renewable energy adoption, and improved internal communication on environmental initiatives. The findings contribute to CSR and sustainability literature by providing empirical evidence from a Kenyan banking context.