In the present work, binder-free CoS_x–graphene nanoplatelets porous structures were coated on Ni(OH)₂ nanosheets using a one-step electrodeposition process. The graphene was produced from the electroreduction of CO2∗ intermediates during the electrodeposition of CoS_x. The surface morphology and interfacial bonding states of CoS_x–graphene@Ni(OH)₂ were sensitive to the deposition time and Co–to–thiourea molar ratio (M_r). The interface reconstruction between CoS_x–graphene NCs and Ni(OH)₂ nanosheets improved the pseudocapacitance performance, which was investigated at different M_r and varying deposition times. Raman spectra verified the presence of graphene and CoS_x mixed phases in all heterostructure electrodes, where CoS₂ was dominant at M_r = 0.2. An XPS analysis indicated the evolution of various interfacial bonding states (CO, CO, CoONi, and SO) between Ni(OH)₂ nanosheets and CoS_x-graphene nanoplatelets, revealing the improvement in the interfacial synergy and concentration of electroactive sites. The hybrid CoS_x-graphene@Ni(OH)₂ NCs at M_r = 0.2 exhibited the highest capacitance of 2116 F∙g⁻¹ at 2 mV∙s⁻¹ and 1618 F∙g⁻¹ at 1 A∙g⁻¹ compared with bare Ni(OH)₂, which achieved 1212 F∙g⁻¹ at 2 mV∙s⁻¹ and 882.88 F∙g⁻¹ at 1 A∙g⁻¹, and other NCs. Bare Ni(OH)₂ nanosheets retained only capacitance retention of 25 % after 2000 cycles, which improved to 70 % in all CoS_x-graphene@Ni(OH)₂ nanoplatelets.