The development of proton conductors that demostrate high conductivity with mechanical resilience is critical for advancing energy devices operating under harsh conditions. Polymer nanocomposites offer a promising route to reconcile these competing requirements through strategic material design. In this work, we report an anhydrous proton-conducting nanocomposite composed of a comb-like crosslinked polymer network and superacidic polyoxometalate (POM) clusters. Poly(glycidyl methacrylate) (PGMA) serves as a comb-like scaffold, rapidly crosslinking with amino-terminated polyethylene glycol (PEG-BA) through a simple blending process. The incorporation of H₃PW₁₂O₄₀ (PW) functions not only as a proton source but also as a mechanical reinforcer via interfacial interactions. The crosslinked framework provides structural stability, while the compatibility between PW and PEG-BA enables continuous proton-conduction pathways through hydrogen bonding and ionic interactions. The optimized nanocomposite achieves a proton conductivity of 8.5 × 10⁻⁴ S·cm⁻¹ at 130 °C and, at the highest crosslinking ratio, a Young’s modulus of 18.1 MPa, along with stable performance over 160 h of extended operation. The modular tunability of both polymer topology and inorganic clusters establishes this approach as a generalizable platform for tailoring ion-transport materials and opens new avenues for high-performance energy technologies.