PurposeCustomer relationships and transforming customers into evangelists are imperative in today's world. Therefore, this study aimed to examine the influence of online brand experience (OBE) on brand evangelism (BEM) via relationship quality (trust-TRT, satisfaction-SAT, and commitment-CMT) by integrating the moderating effects of brand reputation (BR), particularly in the Vietnamese banking sector.Design/methodology/approachThis research obtained data from 486 Vietnamese customers who routinely used online banking services. The analysis was performed using structural equation modeling.FindingsThe findings demonstrate that OBE directly/indirectly positively affects BEM via relationship quality (TRT, SAT, CMT). Likewise, this study identified relationship quality (TRT, SAT, CMT) as an important mediator. Finally, the findings demonstrate that the moderation effects of BR significantly improved relationship quality (TRT, SAT, CMT) in the banking industry.Practical implicationsThis study showcases the significance of OBE in increasing brand evangelists in the financial sector. Thus, this study assists Vietnamese bank managers in creating new branding strategies to foster long-lasting customer relationships.Originality/valueThis original study contributes to the commitment-trust theory and signaling theory by examining the impact of the OBE on brand evangelism via relationship quality by considering the moderating effect of brand reputation in the Vietnamese banking sector.