<p>The Internet of Things (IoT) is a rapidly growing technology that connects virtual and physical things, allowing diverse services without direct human intervention. By 2025, it will consist of billions of interconnected devices. However, the centralized architecture of the IoT poses significant security challenges, including a single point of failure, vulnerabilities in security measures, privacy concerns, transparency issues, and data integrity issues. The IoT is vulnerable to attacks targeting sensors, gateways, platforms, and infrastructure. It is essential to address these challenges by implementing robust security mechanisms, such as authentication, privacy preservation, data integrity, resilience against malicious attacks, simplicity of use, and scalability. This survey focuses on two techniques to improve the security of the Internet of Things: using biometrics as a security measure and integrating blockchain technology. This study explores the various security challenges of the Internet of Things and its Explores recent advances in IoT biometric systems, focusing on security protocols, authentication techniques, privacy measures, and encryption methodologies. It categorizes these systems according to various biometric characteristics and the number of features used. The study highlights the necessity of transitioning from a centralized IoT architecture to a decentralized ledger system. It also investigates the various potentials of blockchain for addressing security concerns. The survey explores the possibility of combining blockchain technology with biometrics within the IoT framework, leveraging robust security protocols and improved blockchain transparency.</p>