The financial services industry faces unprecedented challenges in data security, privacy protection, and regulatory compliance as digital transformation accelerates. Blockchain technology has emerged as a revolutionary solution for secure data management in financial systems, offering immutable, transparent, and decentralized approaches to handling sensitive financial information. This comprehensive review examines the application of blockchain technology in financial data management, analyzing key implementations including distributed ledgers, smart contracts, digital identity verification, and cross-border payment systems. The technology's cryptographic foundations, consensus mechanisms, and distributed architecture provide enhanced security features that address traditional vulnerabilities in centralized financial systems. Case studies from leading financial institutions demonstrate measurable improvements in transaction security, operational efficiency, and regulatory compliance. Benefits include reduced fraud rates by 40-60%, transaction processing time reductions of 70-80%, and significant cost savings in cross-border payments. However, challenges including scalability limitations, energy consumption concerns, regulatory uncertainty, and integration complexity must be addressed for widespread adoption. This article analyzes current blockchain implementations in financial services, evaluates security mechanisms, examines regulatory frameworks, and identifies future directions for secure financial data management. The findings suggest that blockchain technology represents a paradigm shift toward more secure, efficient, and transparent financial systems, requiring strategic adoption approaches and collaborative industry standards to realize full potential.