In this paper, we synthesized several nanostructures, including nanoflakes-, nanosheets-, and nanopetals-like NiCo2S4 flexible electrodes on a flexible stainless-steel substrate, by using successive ionic layer adsorption and reaction method for high-performance supercapacitor application. The as-prepared NiCo2S4 electrodes were structurally and morphologically characterized by X-ray diffraction (XRD), field emission scanning electron (FE-SEM) microscopy, transmission electron (TEM) microscopy, and the supercapacitance evaluated using electrochemical measurements. The nanoporous, three-dimensional interconnected nanosheets-like NiCo2S4 arrays are excellent candidate electrodes for supercapacitor application, demonstrating a high specific capacitance, and long time charge/discharge ability. The calculated values of specific capacitance shows the number of deposition cycles influences the surface morphology, which is confirmed by the FE-SEM and electrochemical testing, displaying a capacitance of 766, 1076, and 921 F g(-1), for 5, 9, and 14 cycles, respectively. The supercapacitor performance confirmed the size of the nanoflakes is appropriate to prepare NiCo2S4 electrodes for high-rate electrochemical supercapacitive energy storage devices.