The Web of Things (WoT), an extension of the Internet of Things (IoT), addresses the interoperability challenges commonly faced by IoT devices. These challenges arise because IoT devices are built using diverse standards and protocols, often resulting in siloed networks and limited compatibility. WoT tackles this issue by leveraging mature and widely adopted web technologies such as Hypertext Transfer Protocol (HTTP) and WebSockets, enabling devices to communicate in a standardized and interoperable manner. This creates a common framework for devices to integrate, exchange data, and interact seamlessly over the World Wide Web. However, WoT also inherits several security limitations from traditional web technologies. For instance, these networks may suffer from insecure communication channels, vulnerable Application Programming Interfaces (APIs), and exposure to a wide range of web-based threats that can be exploited by malicious actors. Blockchain technology offers a promising approach to strengthening the security of the WoT by introducing decentralized trust mechanisms and tamper-resistant data storage. Its core features such as immutability, cryptographic integrity, and decentralized identity management can help ensure secure IoT device authentication, transparent data provenance, and resistance to unauthorized modifications. By integrating blockchain into WoT architectures, it becomes possible to mitigate common vulnerabilities like spoofing, data tampering, and single points of failure, thereby enhancing the overall resilience and trustworthiness of WoT ecosystems. This chapter aims to demonstrate how blockchain technology was integrated into WoT environments to address existing security challenges.