This research study aims to investigate the relationship between corporate social responsibility (CSR)-related communication on social media and brand advocacy behavior of retail banking customers in a developing country. This study also proposes a dual mediating mechanism of customer engagement and customer-company identification in the above-proposed relationship. The data were collected from retail banking customers with the help of a self-administered questionnaire (n = 356). To test the hypothesized relationships, a theoretical model was developed in this study. For hypothesis testing, we used the structural equation modeling (SEM) technique in AMOS software. The empirical analysis results confirmed our theoretical assumption that the manifestation of CSR-related communication on social media by a bank significantly influenced the advocacy behavior of retail banking customers. Our study also confirmed the mediating function of customer engagement and customer-company identification. The findings of this study offer different implications for the banking sector. For example, our study highlights the critical role of CSR-related communication on social media for meaningful customer-brand relationships by promoting the advocacy behavior of customers.