Polymer dielectrics for electrostatic energy storage exhibit low energy density, low efficiency, and poor reliability at high temperatures, limiting the application of film capacitors in harsh environments. Designing wide bandgap structures, introducing carrier traps and constructing carrier barriers are effective strategies for optimizing the energy storage performance of polymer dielectrics. However, the dominant factors that inhibit carrier transport behavior remain unclear. Here, an all-organic polymer dielectric with dominating carrier traps and synergizing electron barriers and repulsion is reported. Benefiting from the dual self-healing mechanism of the gas-condensation phase, the all-organic polymer dielectric shows exceptional breakdown self-healing ability. At 200 °C, the all-organic polymer dielectric achieves exceptional high-temperature energy storage performance and reliability with a discharged energy density of 6.06 J cm−3, a charge–discharge efficiency of above 90%, and a charge–discharge cycling stability of 80 000 cycles after breakdown self-healing, which far exceed those of the existing polymer dielectrics with self-healing ability. Furthermore, the high-temperature-resistant stacked film capacitor device fabricated with the all-organic composite film exhibits excellent capacitance stability. The combination of superior energy storage characteristics, reliability, and device capacitance demonstrates the promising application of the all-organic composite dielectric in harsh electrification environments.