Nickel hydroxide as a potential electrode material was widely used in supercapacitor, but its electrochemical performance is limited due to its low conductivity, insufficient structure and weak stability. In this work, we reported a simple “one-pot” hydrothermal method of vertically growing cobalt-nickel hydroxide (Co-Ni-OH) and rGO nanosheets on conductive carbon cloth (Co-Ni-OH/rGO/CC). We demonstrated that the capacitive performance of Co-Ni-OH electrode could be significantly improved by adding rGO with uniform vertically growing nanostructure, which shortened ion diffusion paths and avoided the interface resistance. As pseudocapacitors, the as-prepared Co-Ni-OH/rGO/CC electrode showed a notable enhanced specific capacitance (151.46 F g−1 at 2.5 A g−1) and a good cycling stability (88.0% after 1000 cycles). Moreover, the symmetric supercapacitor composed of two as-prepared Co-Ni-OH/rGO/CC electrodes achieved a high energy density of 30.29 W h kg−1 at a power density of 1500 W kg−1 (based on active materials) and remarkable cycling stability (85.6% after 3000 cycles). This finding provides a simple and effective way to fabricate a promising electrode material for high-performance supercapacitor and other energy storage device.