The purpose of this study is to investigate the factors that influence the implementation of social media marketing tactics by banks in Vietnam. Through a mixed-methods approach, including both qualitative interviews on 20 Bankers at 10 banks in Vietnam and quantitative surveys on 480 customers, insights are gathered from marketing executives, managers, and customers of various banks. The study explores the motivations driving banks to leverage social media, such as expanding market reach, enhancing customer experience, and fostering brand loyalty. Simultaneously, it investigates the challenges banks encounter in this process, including regulatory constraints, data security concerns, and the need to strike a balance between personalized engagement and privacy preservation. The study also clarifies the effects of social media marketing deployment on Vietnamese banks. This includes improved customer engagement, increased brand visibility, and potential business growth. Additionally, the study highlights the emergence of new communication paradigms, where banks transition from traditional one-way communication to interactive and dialogue-driven engagement. The findings of this research contribute to both theoretical and practical aspects of marketing and digital transformation in the banking sector. By understanding the dynamics of social media adoption, banks can make informed decisions in designing effective marketing strategies that resonate with the preferences and behaviors of Vietnamese consumers. This study emphasizes the increasing importance of social media marketing in Vietnam's banking sector.