This research investigates the differences in the adoption, usage behaviors, and user experiences of the Unified Payments Interface (UPI) between two generational groups: Gen Z (18–24 years) and Millennials (25–40 years) in India. UPI, an advanced real-time digital payment system, has played a pivotal role in transforming India’s financial landscape by enabling seamless peer-to-peer (P2P) and peer-to-merchant (P2M) transactions. While UPI has achieved widespread adoption, there remains a notable gap in academic research regarding the generational variations in how UPI is perceived and utilized. This study aims to fill that gap by identifying the key factors that influence UPI adoption, trust, user satisfaction, and the challenges encountered by each generation. A cross-sectional survey was conducted with 200 participants, equally divided between Gen Z and Millennials, to gather insights on UPI usage frequency, awareness of advanced features such as UPI Credit, and the impact of digital literacy, security concerns, and trust. The findings reveal that Gen Z exhibits a stronger inclination toward adopting UPI, driven by its convenience, speed, and user-friendly interface. In contrast, Millennials express greater concerns about transaction security, reliability, and system performance. Statistical methods such as independent samples t-tests and one-way ANOVA were utilized to analyze the differences in usage patterns between the two generational cohorts. The results provide valuable insights for fintech developers, policymakers, and financial institutions looking to enhance UPI’s user engagement, particularly in promoting digital financial inclusion and advancing the cashless economy initiative. Furthermore, the study offers practical recommendations for improving UPI’s operational efficiency, security measures, and user engagement across different demographic groups, supporting the broader goals of technology acceptance and financial digitalization in emerging markets.