Introducing asymmetry in carbon colloids can enrich their already broad merits; however, the tailored synthesis of asymmetric carbon colloids remains a great challenge. Herein, we report the synthesis of asymmetric semi-yolk–shell carbon spheres (semi-YSCS) with rich N-doping (3.9 at%), raspberry-like rough surface, abundant mesopores, and uniform particle size (∼600 nm). An interface-induced heterogeneous contraction mechanism is proposed. The unique structural features endow the semi-YSCS a high specific capacitance (283 F g–1 at 1 A g–1), favorable cycling stability, and superior rate performance in aqueous supercapacitors. This work provides new insights into the rational design of asymmetric carbon colloids.