This study investigates the evolving role of fintech in shaping global financial systems, with a focus on three interlinked dimensions: (i) integration of Environmental, Social and Governance (ESG) principles into fintech growth; (ii) the disruptive impact of fintech on the traditional financial ecosystem; and (iii) the feasibility of replicating India’s digital public infrastructure model (e.g., UPI) in other developing economies, such as Brazil, Indonesia and Nigeria. Using a mixed-method design, the study combines quantitative trends with qualitative policy analysis across macro, firm and cross-country levels, drawing on the BIS, IMF, World Bank RBI/NABARD reports and firm-level Environmental, Social and Governance (ESG) disclosures, such as Paytm’s TUV-assured BRSR. Comparative benchmarking further assesses India’s fintech infrastructure against Brazil’s Pix, Indonesia’s QRIS and Nigeria’s mobile money frameworks to evaluate scalability and policy adaptability. Findings highlight that fintech integration of Environmental, Social and Governance (ESG) principles—through green finance, sustainability-linked products—enhances corporate credibility and is associated with revenue growth. At the industry level, fintech platforms are shown to reshape financial intermediation by lowering transaction costs and expanding credit access. Cross-country benchmarking indicates that replicating India’s digital public infrastructure in Brazil, Indonesia and Nigeria hinges on governance, interoperability and institutional trust. The study contributes by bridging macro-level investment flows, micro-level corporate strategies and cross-country policy frameworks, offering actionable insights for policymakers and industry stakeholders seeking to balance innovation and stability in the global fintech ecosystem.