Flexible self-charging capacitor systems, which exhibit the combined functions of energy generation and storage, are considered a promising solution for powering flexible self-powered electronics. Here, we present a new approach to demonstrate a flexible self-charging, ultrafast, and high-power-density (SUHP) capacitor system by integrating an aerosol-deposited nanograined relaxor ferroelectric Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PMN-PT) capacitor and piezoelectric Pb(Zr-x,Ti1-x)O-3 (PZT) harvester. The as-designed flexible SUHP capacitor system can generate electric energy with an open-circuit voltage of 172 V and a short-circuit current of 21 mu A under a biomechanical bending force of human fingers. This energy can be stored in the integrated flexible capacitor part and then discharged with a high energy density of 2.58 J/cm(3) within an ultrafast time of 480 ns. Moreover, a high power density of 5.38 MW/cm(3) from the flexible SUHP capacitor suggests that the proposed approach for self-charging and energy storage may be an efficacious way to drive future flexible pulsed-power electronic devices.