This study investigates the determinants of trust formation and fintech adoption intentions among rural consumers in Vietnam, addressing a critical gap in understanding financial inclusion dynamics in emerging economies. Employing a mixed-methods approach combining structural equation modeling (SEM) and fuzzy-set qualitative comparative analysis (fsQCA), this research examines 486 rural Vietnamese consumers across six provinces. The theoretical framework integrates the Unified Theory of Acceptance and Use of Technology (UTAUT2) with institutional trust theory and social cognitive theory to elucidate the complex pathways through which trust emerges in resource-constrained environments. The findings reveal that perceived usefulness (β = 0.342, p < 0.001) and social influence (β = 0.287, p < 0.001) significantly predict trust formation, while institutional support moderates the relationship between trust and adoption intention (β = 0.194, p < 0.01). The fsQCA analysis identifies four distinct configurational pathways to high adoption intention, demonstrating that multiple combinations of antecedents can achieve the same outcome. Notably, the presence of strong institutional support can compensate for lower levels of technological self-efficacy in driving adoption intentions. This research contributes to financial inclusion literature by providing empirical evidence of trust's mediating role in technology acceptance within collectivist, hierarchical societies and offers practical implications for policymakers and fintech providers seeking to bridge the digital financial divide in Southeast Asian rural markets.