Nickel hydroxide is widely utilized for the cathode material of asymmetric supercapacitors due to high electrochemical performance and low cost. However, considering its poor electrical conductivity as well as short cycle life, Ni(OH)2 is not capable of applying to high performance supercapacitors. An efficient solution is to fabricate the activated graphene nanosheets (AGNSs)/spinule-like Ni(OH)2 composite by controllable complex-precipitation method. The electrochemical measurement results demonstrate that AGNSs/spinule-like Ni(OH)2 composite as cathode material for supercapacitor has high specific capacitance of 2450 F g−1 at 1 A g−1 and excellence cycling capacity (1499 F g−1 after 5000 cycles at 10 A g−1). The asymmetric supercapacitor (ASC) displays a superior energy density of 55.6 Wh Kg−1 at power density of 1628 W kg−1, as well as rate capacity. These excellent electrochemical properties are attributed to the synergy effect of activated graphene and nickel hydroxide.