The sustainable blue economy represents a critical yet underfinanced frontier in global climate and biodiversity governance. Despite its potential to drive inclusive growth and ocean resilience, investment flows into marine and coastal sectors remain fragmented, opaque, and institutionally constrained. This article examines how financial technology (FinTech) innovations can build a digital infrastructure to mobilize and govern blue economy investments effectively. Using a mixed-method framework that integrates case studies of digital blue bonds, blockchain-based traceability systems, and artificial intelligence-driven impact assessment platforms, the paper develops a conceptual model for a digital blue finance infrastructure. The model highlights the interoperability between tokenized financing instruments, distributed ledger verification, and data analytics for transparent monitoring of marine investment outcomes. Empirical findings suggest that FinTech-enabled systems can significantly enhance accountability, reduce transaction costs, and attract blended capital into sustainable ocean projects. Furthermore, the study situates digital blue finance within emerging global policy frameworks such as the EU Sustainable Finance Strategy, the United Nations Ocean Decade, and the Association of Southeast Asian Nations blue finance initiatives. By linking FinTech architecture with environmental governance, the paper contributes to both sustainable finance theory and practical innovation design. It argues that digitalization is not merely a financial enabler but a structural catalyst for scaling equitable, accountable, and climate-aligned blue economy investments. Received: 26 October 2025 \textbar Revised: 26 January 2025 \textbar Accepted: 25 February 2026 Conflicts of Interest The author declares that he has no conflicts of interest to this work. Data Availability Statement Data sharing is not applicable to this article as no new data were created or analyzed in this study. Author Contribution Statement Kolawole Afuwape: Conceptualization, Methodology, Validation, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration.