Nanostructured porous carbon materials highlighted by activated carbon and its derivatives, which possess an interconnected porous architecture and excellent chemical stability, have shown considerable research interest in supercapacitors. However, the fabrication of porous carbons with a well-defined morphology and engineered graphitic structure presents an enormous challenge. Herein, a confined catalytic pyrolysis strategy with the aid of FeMgAl-layered double hydroxides is proposed to fabricate the porous carbon nanosheet (PCNS), employing coal tar pitch as a low-cost carbon source. The as-obtained PCNS demonstrates a specific surface area of 2696 m(2) g(-1) and an ample graphitic structure, which enables a remarkably high specific capacitance of 314 F g(-1) and excellent rate capability of 74% at 30 A g(-1) as the electrode for the supercapacitor. Furthermore, a two- electrode cell assembled by the PCNS also delivers a charge storage performance of 12.4 Wh (energy density) at an ultrahigh output power of 16.0 kW kg(-1), which is increased to 26.9 Wh kg when the output power is retained at 1.3 kW kg(-1). The current work revealed the promising potential of the PCNS electrode for the supercapacitor by replacing the conventional porous carbon materials.