Quantum computing is rapidly advancing from a theoretical possibility to a transformative force in financial systems. With its high-dimensional computational capacity, quantum technology is promising for enhancing risk modelling, fraud detection and transaction efficiency. However, it also seriously threatens cryptographic security, regulatory coherence and systemic stability. This paper critically analyses the risks introduced by cryptographically relevant quantum computers and assesses the readiness of legal and institutional frameworks to respond. Focusing on the UK financial regulatory environment, the study proposes a quantum-safe integration roadmap grounded in post-quantum cryptography, adaptive regulatory models and sector-wide governance strategies. The paper argues for anticipatory regulation that embeds enforceable standards and strategic collaboration across public and private stakeholders through an interdisciplinary approach combining legal analysis and financial risk modelling. The UK’s leadership in quantum policy positions it to shape international norms in secure quantum adoption. Finally, the paper offers an analytical framework to ensure that quantum innovation reinforces rather than destabilises data integrity, financial resilience and public trust.