<p>The development of environmentally friendly energy-storage devices capable of rapid charging and discharging has become essential for addressing the depletion of energy resources and the growing societal demand for energy storage. In this study, waste newspaper was used as the carbon precursor and potassium bicarbonate (KHCO₃) as the activating agent to prepare newspaper-derived porous carbon featuring coexisting micropores and mesopores through high-temperature activation. The resulting samples were characterized using various techniques, and their electrochemical performance was evaluated in three-electrode and two-electrode configurations. The sample prepared at 800 °C with a holding time of 2 h, denoted NPK-800–2, exhibited a well-developed porous structure and a large specific surface area of 1632.81 m² g⁻¹. NPK-800–2 also demonstrated excellent electrochemical performance. In a three-electrode configuration using 6 M KOH as the electrolyte, the sample delivered a specific capacitance of 186.9 F g⁻¹ at a current density of 0.5 A g⁻¹ and retained 85% of its capacitance when the current density was increased to 5 A g⁻¹. The symmetric supercapacitor assembled using NPK-800–2 achieved an excellent energy density of 12.39 Wh kg⁻¹ at a power density of 500 W kg⁻¹ and exhibited outstanding cycling stability, showing a capacitance retention of 109% after 10,000 cycles while maintaining a Coulombic efficiency of approximately 100% throughout the cycling process. These results demonstrate that waste newspaper can serve as an efficient carbon precursor for preparing high-performance electrode materials for supercapacitors with practical application potential.</p>