Ultra-thin Ni(OH)2 nanosheets and reduced graphene oxide (Ni(OH)2/rGO) composite was successfully synthesized via a facile solvothermal method. Field emission scanning electron microscopy and high-resolution transmission electron microscopy measurements show the porous Ni(OH)2 nanosheets are flatly supported on rGO sheets to form a two-dimensional composite with high specific surface area (210 m2 g−1). Serving as the electrode material for supercapacitors, the Ni(OH)2/rGO composite exhibits high specific capacitance (1886 F g−1 at 5 A g−1, 1362 F g−1 at 30 A g−1) and excellent cycling stability (∼70% capacity retention after 1000 cycles at 10 A g−1) due to its unique two-dimensional heterostructure and synergistic effect between Ni(OH)2 and rGO, indicating two-dimensional Ni(OH)2/rGO composite is promising electrode material for the electrochemical energy storage applications.