Studies have shown that an organization’s corporate social responsibility (CSR) activities affect customer behaviors such as loyalty and satisfaction. In spite of this, the role of social media in informing customers about a brand’s CSR activities and in fostering customer advocacy behavior (CADB) has been underexplored. To fill this knowledge gap, this study investigates the relationship between the CSR-related communication of a banking organization and CADB. This study also examines how emotions such as customer–company identification (CCI) and gratitude as a mediator and a moderator. Using a self-administered questionnaire (n = 302), we collected data from banking customers. Hypotheses were evaluated by using structural equation modeling, which revealed that CSR positively predicts CADB, whereas there are mediating and moderating functions of CCI and GA. Theoretically, this study highlights the role of human emotions in behavior formation from the standpoint of social media. Practically, this study provides important insights for the banking sector’s administrators to realize the important role of CSR communication, using different social networking websites, for converting customers into brand advocates.