The rapid expansion of Internet of Things (IoT) devices within smart home and office environments has introduced new security challenges, particularly in authentication and access control. Many users, even those with technical expertise, often lack adequate mechanisms to safeguard their privacy against cyberattacks targeting IoT systems. To address these vulnerabilities, this work integrates blockchain technology with facial recognition to provide a secure, reliable, and user-friendly authentication framework. The proposed system employs facial biometric verification alongside Ethereum-based smart contracts to ensure decentralized, tamper-resistant access control. A comprehensive performance and security analysis was conducted to evaluate the system’s effectiveness. Experimental results demonstrate that the proposed method offers efficient execution times, low transaction costs, and strong resistance to common cyberattacks, confirming its suitability for protecting IoT devices in smart home and office settings.