<p>The Internet of Things, commonly known as IoT, has significantly shaped connectivity and usability in various fields, offering numerous services to simplify our daily lives. However, there is a need to be concerned about the security and privacy of the network to protect it from possible threats that pose substantial risks to the integrity of IoT systems. One of the major concerns is user authentication. To safeguard the IoT network against potential attacks and unauthorized access, a robust user authentication mechanism is necessary. Moreover, for traditional user authentication, the user information is stored in a centralized storage, which is vulnerable to potential breaches and attacks. To address these vulnerabilities, a decentralized and immutable blockchain-based technology known as Self-Sovereign Identity (SSI) can offer a more secure alternative to enhance the user authentication mechanism. In this paper, an architecture is proposed to enhance the user authentication process in the Internet of Things environment by employing a blockchain-based SSI system. With the integration of distributed ledger technology, the security issues related to the centralized network structure can be mitigated. This integration also enhances security and operational efficiency by effectively mitigating the risks associated with identity misuse. The proposed architecture is simulated using the Mininet-WiFi emulator for the network and the Ethereum blockchain to deploy the smart contract for enhancing the user authentication procedure. The proposed architecture is compared with other existing authentication mechanisms and found that the authentication time of the proposed authentication methodology is lower than that of other authentication mechanisms. The security of the user authentication system has also been testing using Scyther tool and it gives satisfactory results.</p>