The formation of vulnerability to natural hazards consists of many driving factors that represent multi-facets of the subjected system. However, the interactions among these components remain unclear and have not been clarified. Examining these internal relationships helps to improve the accuracy of vulnerability assessments and provides needed focus in flood management. This study employed partial least squares structural equation modeling (PLS-SEM) to discover the interrelationship of household flood vulnerability determinants in Cambodia's floodplain and Vietnam's Mekong River Delta. The results show that demographics and social capital have direct influences on flood exposure. In this paper, socioeconomic status can reduce flood effect levels through the mediation of coping capacity. In addition, heterogeneity was also observed between Vietnamese and Cambodian families, highlighting the influence of context on understanding social vulnerability. As the two countries are under threat from hydropower and climate change that profoundly affect flooding, flood management strategies should be improved. The study suggests that the focus should be placed with socioeconomic and coping capacity to sustainably strengthen resilience against flooding.