Unified Payments Interface (UPI) has become central to India’s digital payment ecosystem, particularly for high-frequency micro-payments among Generation Z users. Ensuring user trust is essential as incidents of fraud, payment failures, and data-use concerns continue to rise. This study identifies and models the structural interdependencies among ten key drivers influencing trust in UPI micro-payments. Using a mixed deductive–inductive approach grounded in UTAUT2, Protection Motivation Theory, and Socio-Technical Systems Theory, the research applies Interpretive Structural Modelling (ISM) and MICMAC analysis to responses from 131 Gen Z users. The results reveal a seven-level hierarchy in which security measures and regulatory assurance form foundational enablers, followed by performance-centric drivers such as speed, reliability, ease of use, and interoperability. Cognitive factors—data transparency and past experience—shape risk appraisal, while fraud concerns, peer influence, and rewards reinforce behavioural trust. The study offers a systems-level understanding of trust formation and actionable insights for strengthening UPI’s reliability and safety.