Supercapacitors are highly attractive in the large-scale energy storage field, but the “trade-off” between the gravimetric capacitance and the volume and area specific capacitance greatly affects their further development. In this work, we developed coralloid-like porous carbon sheets (CPCS) with double support structure via a bidirectional anchoring strategy, exhibiting ultra-low specific surface area (26.95 m² g⁻¹) and moderate packing density (0.75 g cm⁻³). In the meantime, the proposed dual-anchor structure model made the interior “self-doping” defects and the exterior “foreign-doping” defects fully exposed, which is seldom obtained by other artificial methods. Based on this, it delivered a superior overall performance in gravimetric, volumetric, and areal capacitances (308.89 F g⁻¹, 231.67 F cm⁻³, and 1146 μF cm⁻²) and stable cyclability (10 000 cycles), which is the highest capacitance reported for polyacrylonitrile-based hard carbon without chemical/physical activation. Considering the low-energy and innovative synthesis route, our work may shed some light on developing advanced carbons promising for supercapacitors.