This study investigates the drivers of passenger loyalty in Vietnam's low-cost airline market, focusing on the mediating role of electronic word of mouth (eWOM) and the moderating role of airline brand image (ABI) in the relationship between perceived value (PV) and passenger loyalty (PL). As the market experiences rapid growth and increased competition, understanding loyalty drivers is crucial for Vietnamese low-cost carriers (LCCs). Utilizing Partial Least Squares Structural Equation Modeling (PLS-SEM) on data from 236 passengers, the findings reveal that perceived value and eWOM significantly enhance PL, with eWOM mediating the perceived value-loyalty relationship. Interestingly, while ABI does not directly affect loyalty, it crucially moderates the impact of perceived value on loyalty. This suggests that a positive ABI amplifies the effect of perceived value on loyalty. The study provides actionable insights for Vietnamese LCCs, emphasizing the need to enhance perceived value through superior service, encourage positive eWOM, and build a strong brand image to foster lasting customer loyalty and gain a competitive edge.