Nature Communications, Published online: 19 August 2026; doi:10.1038/s41467-026-76855-z Protein hydrogels are valued for their biocompatibility and biodegradability, but their use has been limited by poor mechanical strength and dehydration. Here, the authors introduce an Ion-Mediated Hydration Engineering strategy that converts free water into bound water, improving chain mobility and stabilizes hierarchical structures.