The rapid expansion of IoT devices, cloud-based services, and mobile platforms has intensified the need for cryptographic systems that balance strong security with low computational overhead. This paper presents a fully redesigned hybrid encryption framework that integrates Elliptic Curve Diffie–Hellman (ECDH) for secure key establishment with high-performance symmetric encryption using AES-GCM and ChaCha20. The proposed model leverages ECC's compact key sizes to reduce computational complexity while providing multi-layered confidentiality, integrity, and authenticity. Experimental evaluation demonstrates a 25–40% improvement in encryption latency, reduced memory usage, and better scalability compared to conventional RSA-based and standalone symmetric approaches. The framework is lightweight, attack-resilient, and optimized for constrained environments such as IoT nodes, wireless sensor networks, embedded controllers, and smart healthcare devices. The study concludes that integrating ECC with modern symmetric primitives forms a robust architecture capable of addressing emerging cyber threats, with future enhancements planned toward post-quantum resilience and adaptive cryptographic mechanisms.