The rapid integration of Internet of Things (IoT) devices within the healthcare domain has revolutionized patient care by enabling real-time monitoring and remote diagnostics. However, this advancement has also introduced significant challenges related to data security, patient privacy, and communication trustworthiness. Conventional communication protocols often fail to safeguard sensitive medical data transmitted across distributed and heterogeneous networks. This paper presents a blockchain-based secure communication framework designed explicitly for Healthcare IoT (H-IoT) environments. The proposed architecture incorporates lightweight blockchain nodes, smart contract-driven authentication, and cryptographic hash functions to establish a decentralized and verifiable communication channel between medical sensors and healthcare providers. The system is evaluated using simulated H-IoT scenarios involving encrypted patient vitals and blockchain-based integrity verification. Experimental results indicate that the framework achieves strong resistance against data tampering, enhances auditability, and ensures high data integrity, all while maintaining minimal latency overhead. The findings demonstrate the framework’s potential as a scalable, secure, and privacy-preserving solution for next-generation medical IoT systems.