An asymmetric NiCo2S4@Fe2O3//MnO2 supercapacitor is reported for the first time. Hierarchical NiCo2S4@Fe2O3 nanoarray with a capacitance of 342 F/g was used as anode. MnO2 nanoarray with enlarged working potential to 1.3 V was used as cathode. The device was operated stably in 0–2.3 V in neutral aqueous electrolyte. The device delivered high energy density (2.29 mWh cm−3) at high power density.