In the work, we develop a novel two-step strategy to synthesize self-supported hexagonal nickel oxide nanoplatelet arrays on Ni foam: precipitating hydroxides followed by calcinating process. These nanoplatelets are composed of a multilayer of ultrathin mesoporous NiO nanosheets. The unique Ni foam-supported mesoporous NiO nanoplatelet arrays electrode promises fast ion and electron transport, large electroactive surface area, and excellent structural stability. As a result, superior pseudocapacitive performance is achieved with large specific capacitance in the range of 1124–864Fg−1 and excellent cycling stability up to 5000 cycles, suggesting their promising application for electrochemical capacitors.