Converting surplus renewable electricity into hydrogen by electrolyzers has been recognized as a promising scheme to reduce renewable energy spillage and to meet the increasing hydrogen demand. However, the scheme is challenged by the inherent spatiotemporal imbalance between renewable energy and hydrogen demand. Seasonal storages and interregional hydrogen supply chains (HSCs) are commonly employed in the literature to eliminate this imbalance, but long-distance hydrogen transportation can be costly. In this paper, we incorporated the electric network (EN) into the HSC for its ability to promptly and economically deliver energy at long distances. The uniform hierarchical time discretization method is utilized to achieve the unified operation of the HSC and the EN. On this basis, an integrated HSC-EN model is elaborated upon to investigate the optimal investment and operation of electrolyzers and storage. Finally, an industrial case in Sichuan province, China is analyzed to illustrate the benefits of incorporating the EN to reduce the investment cost and improve electrolyzers’ utilization.