While blockchain technology promises immutable transparency for democratic processes, reconciling the requisite voter privacy with system scalability remains a critical challenge, often necessitating a trade-off between decentralization and computational efficiency. This paper presents ZKHC-Voting, a novel hybrid blockchain e-voting architecture designed to resolve the inherent conflict between public auditability and voter privacy. By decoupling the identity management layer onto a private chain (Registry Chain) and executing voting on a public chain (Voting Chain) via a trust-minimized header verification bridge, ZKHC facilitates voter validity verification using Zero-Knowledge Proofs (ZKP) without disclosing voter identity. Experimental results on the Sepolia testnet demonstrate the system’s superior performance: it completely eliminates gas costs for the registration phase, reducing from \(\approx \) 979,000–19,000,000 gas in single-chain models to 0 while maintaining stable voting costs at \(\approx \) 315,614 gas. Notably, the architecture exhibits high scalability, with a Merkle tree reconstruction time of only 244.55 s for 1 million voters, setting a new performance benchmark for large-scale decentralized governance systems.