Abstract Achieving high mechanical strength and environmental stability is critical for hydrogels in demanding engineering scenarios. Crystalline hydrogels hold promise because their crystallites act as physical crosslinks and energy dissipators; however, precise control over crystalline architecture remains underexplored. Inspired by industrial thermoplastic processing, we report an ASGS strategy for crystalline hydrogels that integrates alkali-induced chain activation (A), ultra-stretching-driven orientation (S), and glycerol-seawater-mediated densification (GS). Alkali treatment yields moderate initial crystallinity with refined nascent crystallites. Ultra-stretching establishes a highly oriented chain network, and subsequent densification achieves maximum crystallinity and highly oriented crystallites. The resultant hydrogels, in the fully hydrated state, combine a tensile strength of 160.0 MPa, a modulus of 746.0 MPa, and a fracture energy of 26.4 kJ·m⁻². The corresponding plastic reaches 414.2 MPa tensile strength while retaining flexibility. This thermoplastic-inspired crystallization engineering provides a scalable paradigm for fabricating strong and stable crystalline hydrogels, promising for load-bearing and harsh underwater engineering applications.