Graphitic carbon nitride (CN) is a cost-effective and easily synthesized supercapacitor electrode material. However, its limited specific capacity has hindered its practical use. To address this, we developed a binary nanostructure by growing nanosized Co3O4 particles on CN. The CN-Co-2 composite, synthesized via thermal decomposition, exhibited a remarkable specific capacity of 280.64 C/g at 2 A/g. Even under prolonged cycling at 10.5 A/g, the retention rate exceeded 95%, demonstrating exceptional stability. In an asymmetric capacitor device, the CN-Co composite delivered 20.84 Wh/kg at 1000 W/kg, with a retention rate of 99.97% over 20,000 cycles, showcasing outstanding cycling stability. Controlled cobalt source adjustments yielded high-capacity electrode materials with battery-like behavior. This optimization strategy enhances energy density by retaining battery-like properties. In summary, the CN-Co composite is a promising, low-cost, easily synthesized electrode material with a high specific capacity and remarkable cycling stability, making it an attractive choice for energy storage applications.