In this work, three dimensional (3D) hierarchical structure electrode of MnO2 nanosheets decorated on needle‐like NiCo2O4 nanocones hybrid arrays on Ni foam is designed by a two‐step hydrothermal process. In this special structure, 3D hierarchical NiCo2O4/MnO2 core/shell composites have high specific surface area and large pore structure, which makes it easier to reach the active site, and shorten the ion transport path. Used as electrode for supercapacitors, the composites can develop their respective strengths, and the synergies between different components can also improve capacitance and speed capacity. The electrochemical results exhibit that the NiCo2O4/MnO2 core/shell electrodes display a large capacitance of 816 F⋅g−1 at the current density of 5 mA⋅cm−2, and show an excellent cycling stability (81% retention after 5000 cycles). Four Asymmetric supercapacitors (NiCo2O4/MnO2//BPC (banana peel), NiCo2O4/MnO2//BHC (buckwheat husk), NiCo2O4/MnO2//PPC (pomelo peel), and NiCo2O4/MnO2//AC (activated carbon)) using the NiCo2O4/MnO2 core/shell as a positive electrode and biochar as a negative electrode are assembled. The results indicate that all the asymmetric supercapacitors deliver a high operation voltage of 1.6 V, and NiCo2O4/MnO2//BPC exhibits excellent specific capacitance (85.4 F⋅g−1 at the current density of 5 mA⋅cm−2), high energy density (30.4 Wh⋅kg−1 at the power density of 133.5 W⋅kg−1) and remarkable cycling stability (only decrease by 12% after 5000 cycles).