In this work, we have prepared 0.25Co-doped NiMoO4 nanosheets by a facile hydrothermal route. The doped samples present a large specific surface area and suitable pore structure, which facilitates contact between the electrodes and the electrolyte. The assembled asymmetric capacitors possess high capacity and power density and show excellent cycle performance. The results demonstrate that the synthesized materials possess promising application prospects in future flexible devices.