<p>Gel polymer electrolytes (GPEs) are conceived to be a good way to build safer lithium/sodium metal batteries by substituting traditional liquid electrolytes. However, it is still very difficult for GPEs to simultaneously achieve high room-temperature ionic conductivity, uniform Na⁺ flow, superior interfacial compatibility, and increased mechanical strength. Herein, a composite gel electrolyte (KNT-PTGPE) with high ionic conductivity of 4.06 mS cm⁻¹ is prepared through chemical crosslinking strategy and the introduction of inorganic nanoparticles. The hybrid gel polymer network is formed by <i>in situ</i> cross-linking modified TiO₂ (KNT), three-armed trimethylolpropane trimethacrylate and poly(ethylene glycol) diacrylate. The resulting 3D interpenetrating network facilitates the absorption of liquid electrolytes and improves the mechanical properties of electrolyte. Theoretical calculation and <i>in situ</i> measurements reveal that the homogeneous TiO₂ fillers with abundant Lewis acid site and polymer network are involved in the solvation process of Na⁺, thus constructing a fast Na⁺ transport channel. Consequently, a stable plating/stripping process lasting over 900 h is achieved due to the uniform distribution of Na⁺ flux and the good mechanical properties of the electrolyte, and the assembled cell exhibits an excellent long-term cycling stability. The approach offers more opportunities to design GPEs for high performance SMBs.</p>