<p>The advancement of flexible wearable electronics demands materials that integrate high conductivity, exceptional mechanical flexibility, and broad environmental adaptability. Although polyoxometalate (POM)-based conductive hydrogels hold great promise, their application is impeded by two critical limitations: poor interfacial compatibility between POMs and polymer matrices, and significant conductivity degradation at low temperatures. To address these issues, we designed a POM-based proton-conductive hydrogel (PVA/P(SBMA-AM)/PW₁₂/PA (PSAWA)) by incorporating zwitterionic sulfobetaine methacrylate (SBMA), phytic acid (PA), and H₃PW₁₂O₄₀ (PW₁₂) into a poly(vinyl alcohol) (PVA)-poly(acrylamide) dual-network matrix. SBMA enhances the loading and dispersion of PW₁₂ within the hydrogel via an electrostatic–steric synergistic mechanism. Concurrently, PA synergizes with PW₁₂ to ensure fast proton migration even at low temperatures by constructing proton-conduction pathways with reduced energy barriers. These design strategies endow the PSAWA hydrogel with ultrahigh proton conductivity (2.71 × 10⁻¹ S cm⁻¹ at 25 °C; 1.06 × 10⁻² S cm⁻¹ at −40 °C), alongside high stretchability, remarkable self-healing capability, effective antibacterial activity, and excellent biocompatibility. Furthermore, flexible biosensors and supercapacitors fabricated using the PSAWA hydrogel demonstrate outstanding performance even at −40 °C. This work offers new insights for developing proton-conductive hydrogels with low-temperature adaptability for wearable electronics.</p>