Graphitic carbon nitride (g-C3N4) is a nitrogen-enriched, thermally stable, and cost-effective material with exceptional electrochemical properties, surpassing those of traditional carbon-based materials, such as graphene. Its high nitrogen content and layered structure make it a promising candidate for advanced supercapacitor electrodes. This study utilized thermal condensation and hydrothermal methods to synthesize bulk g-C3N4 (BGCN) and sheet g-C3N4 (SGCN). BGCN and SGCN, through X-ray diffraction, confirmed their structural order; Fourier-transform infrared spectroscopy and Raman spectroscopy identified key functional groups and vibrational modes, X-ray photoelectron spectroscopy provided detailed elemental composition and bonding information and scanning electron microscopy unveiled the bulk nature of BGCN and the novel ribbon-stacked morphology of SGCN. Electrochemical analysis, carried out using 1 M KOH as the electrolyte, demonstrated excellent performance for the ribbon-stacked SGCN. Cyclic voltammetry exhibited good charge storage behaviour, with DUNN’s method at 5 mV/s showing a capacitance contribution of 76.8% from surface capacitive processes and 23.1% from diffusion-controlled mechanisms. Galvanostatic charge–discharge measurements showed a remarkable specific capacitance of 328 F/g at 1 A/g. Electrochemical impedance spectroscopy indicated a low charge transfer resistance (Rct) of 12.97 Ω and a solution resistance (Rs) of 5.49 Ω, supporting efficient ion transport. The columbic efficiency was found to be 90%, and cyclic stability tests confirmed a capacitance retention of 96% over 3000 cycles. SGCN’s distinctive ribbon-stacked morphology facilitates superior electrochemical performance, rendering it a compelling material for scalable, high-performance electrodes in future supercapacitor applications.