Mechanically robust electrolytes with high ionic conductivity play an essential role in carbon fiber (CF) structural batteries that simultaneously store energy and bear mechanical loads. However, multifunctional composite electrolytes are rarely developed, especially for air-stable and safe structural Zn-ion batteries. Herein, a composite electrolyte GF-SPE is designed and fabricated by integrating ionic conductive poly(ethylene glycol) diacrylate (PEGDA)-based solid-state polymer electrolyte (SPE) matrix and glass fiber fabric (GF) reinforcement, which simultaneously exhibits mechanical robustness and high ionic conductivity, facilitating homogeneous Zn electrodeposition without obvious side reaction, such as dendrite growth, corrosion et al. Therefore, the symmetric cells Zn//GF-SPE//Zn cell can cycle stably for more than 800 h at 1 mA cm−2. The carbon fiber structural battery fabricated with composite structural electrolyte GF-SPE delivers a high energy density of 19.35 Wh kg−1 based on the total mass of the whole device and cycling stability over 1,000 cycles in extreme environments. Furthermore, the high capacity of structural Zn-ions batteries can be maintained when they withstand flexural stress of over 120 MPa. The in-situ mechanical-electrochemical testing further confirms the priority of structural Zn-ion batteries.