This paper presents a hybrid on–off chain blockchain architecture tailored for enhancing the security and efficiency of Electronic Health Records (EHRs). By combining on-chain immutability with off-chain scalability, the proposed approach ensures data integrity and confidentiality while optimizing performance. Key components include a permissioned blockchain network, and smart contracts for access control. Challenges such as interoperability and regulatory compliance are addressed, alongside a security analysis. This hybrid blockchain solution offers a promising pathway for secure EHR management in healthcare systems.