The Unified Payments Interface (UPI), launched by India’s National Payments Corporation of India (NPCI) in 2016, has fundamentally transformed the digital payment landscape, evolving from a disruptive innovation to essential financial infrastructure. This research examines how consumer trust dynamics have shifted in the post-UPI era, where UPI processes over 20 billion monthly transactions and accounts for 84% of India’s digital payments [1]. The study integrates Technology Acceptance Model (TAM) and Unified Theory of Acceptance and Use of Technology (UTAUT) constructs with trust theory to develop a comprehensive framework for understanding consumer trust in mature digital payment ecosystems. Key findings reveal that trust determinants have evolved from brand-based considerations to infrastructure-level confidence, encompassing perceived security, data privacy architectures, regulatory oversight, and interoperability. The research identifies an “invisible trust” paradox where ubiquitous infrastructure becomes taken for granted, potentially creating new vulnerabilities. With UPI handling 50% of global real-time digital transactions and expanding internationally, understanding these trust dynamics is crucial for policymakers, platform designers, and financial institutions navigating the post-infrastructure phase of digital payments evolution.