As financial institutions accelerate their digital transformation journeys, the scalability and effectiveness of Customer Relationship Management (CRM) data migration frameworks have become pivotal to operational continuity and customer-centric innovation. This systematic review synthesizes current academic and industry literature to evaluate scalable CRM data migration frameworks tailored for financial institutions undergoing complex digital transitions. Grounded in technological and organizational theory, the study analyzes the structural design of CRM systems, core principles of high-volume data migration, and the impact of modernization strategies such as cloud adoption and legacy system reengineering. Applying PRISMA-based methodologies, the review categorizes and compares frameworks across key dimensions including automation, cost-efficiency, fault tolerance, and compliance. Findings reveal that while scalable technical solutions exist, successful implementation depends equally on robust governance, risk management, and change enablement strategies. The paper concludes with strategic recommendations for stakeholders and outlines research opportunities in AI-enhanced migration, hybrid architectures, and longitudinal performance assessment. These insights aim to bridge the gap between technological capabilities and institutional readiness in CRM transformation initiatives.