The development of new generation dielectric materials toward capacitive energy storage has been driven by the rise of high-power applications such as electric vehicles, aircraft, and pulsed power systems. Here we demonstrate remarkable improvements in the energy density and charge-discharge efficiency of poly(vinylidene fluoride) (PVDF) upon the incorporation of core-satellite structures, namely NaNbO3(NN)@polydopamine (PDA)@Ag nanowires. As compared to the NN NWs/PVDF and NN@PDA NWs/PVDF nanocomposites, the NN@PDA@Ag NWs/PVDF nanocomposites exhibit greatly enhanced energy density and significantly suppressed energy loss. As a result, the NN@PDA@Ag NWs/PVDF nanocomposite films with optimized filler content exhibit an excellent discharge energy density of 16.04 J cm-3 at 485 MV m-1, and maintain a high discharge efficiency of 62.8%. Moreover, the corresponding nanocomposite films exhibit a superior power density of 2.1 MW cm-3 and ultra-fast discharge speed of 153 ns. Ultimately, the excellent dielectric and capacitive properties of the polymer nanocomposites could pave the way for widespread applications in modern electronics and power modules.