Electronic word of mouth (e-WOM) studies have been popular as a result of the rise of social networks and e-commerce. Nonetheless, there has been very little research on CSR communication associated with e-WOM. The purpose of this study is to see how e-WOM, as a means of sharing information about CSR activities, affects Vietnamese B2C e-commerce customers’ trust. With the help of 349 online consumers in Hanoi, data was gathered through online and direct survey methods. As a result of the findings, we can conclude that the relationship between e-WOM and customer’s trust is moderated by CSR messages.  The authors provide a variety of solutions based on the research findings to assist B2C organizations in improving their communicating information about CSR activities to achieve the optimum marketing effectiveness