Sixth-generation networks (6G) are predicted to be started use by 2030, supporting the complex communication requirements of a data-centric civilisation where everything is interconnected. The research and academics started to analyse the 6G wireless network technology after the implementation of the 5G technology globally. The 6G networks will be more deliberate to extend cell communication and network capabilities to reach ultra-high-speed connectivity which could precede into the regions where the generation before could not. The new security features need to be advanced to guarantee the data is secure and protect the network from being invaded. The technology of blockchain and integration of the Internet of Things (IoT) has the prospect to revolutionize the networking system. This paper explores the applications of blockchain in IoT networking, addressing challenges such as security, scalability, and trust. Blockchain also enhances security, audibility, and traceability in IoT networks. Use cases in the supply chain, management, healthcare, and smart cities demonstrate the benefits of this integration. Challenges include scalability, energy consumption, interoperability, and privacy concerns. Future research should focus on addressing these challenges to fully exploit the potential of IoT blockchain applications in networking systems.