Recently, structural supercapacitors have attracted considerable attention due to their concurrent capability to store electrochemical energy and support mechanical loads. However, the greatest challenge in realizing an integrated electro-mechanical system is the development of highly compatible electrodes and structural electrolytes with superior mechanical and electrochemical performance. Here, a structural supercapacitor assembled with a 3D rGO@MnO₂ nickel foam electrode and polyacrylic acid–Portland cement–KOH electrolyte is reported to solve the challenge for the first time. The resulting rGO@MnO₂ electrode exhibits a high areal capacitance of 1.84 F cm⁻² at 0.5 mA cm⁻², with the areal capacitance remaining at 1.13 F cm⁻² even at a current density of 40 mA cm⁻². The structural electrolyte with 6 wt% polyacrylic acid–Portland cement–KOH shows the best combination of an ionic conductivity of 2.13 mS cm⁻¹ and a compressive strength of 28.5 MPa. The resulting asymmetric structural supercapacitor with an areal capacitance of 51.5 mF cm⁻² at 0.1 mA cm⁻² is superior to those reported in latest studies based on carbon materials and resin, which suggests its potential application in structural energy storage for civil engineering.