The integration of post-quantum cryptography with blockchain technology represents a transformative leap in securing digital transactions against emerging quantum threats. Blockchain, characterised by its decentralised and tamper-evident data structure, relies on cryptographic techniques to ensure the integrity and confidentiality of transaction data. However, the advent of quantum computing poses significant challenges to the cryptographic foundations of blockchain, particularly asymmetric key systems like RSA. This study delves into the vulnerabilities introduced by quantum advancements and evaluates post-quantum cryptographic techniques, specifically lattice-based and hash-based cryptography, as potential safeguards. Lattice-based cryptography, relying on complex mathematical constructs like the shortest and closest vector problems, offers robust resistance to quantum attacks. Similarly, hash-based cryptographic methods, leveraging the immutability and collision resistance of hash functions, provide an alternative framework for securing blockchain data. The paper examines these methods, discussing their strengths, limitations and implementation challenges in a blockchain context. While no new algorithms are proposed, the analysis underscores the urgency of adopting quantum-resistant cryptographic protocols to preserve the security and reliability of blockchain systems in the quantum era. By addressing these emerging risks, this research aims to contribute to the development of a resilient blockchain ecosystem capable of withstanding the computational capabilities of future quantum technologies.