A novel sandwich-structured polymer-based nanocomposite with different dielectric fillers stacked together was fabricated employing a layer-by-layer casting process. In the sandwich-structured composite poly(vinylidene fluoride)-based film, the outer layer with TiO₂ nanoparticles increased the electric displacement while the central layer with paraelectric BaSrTO₃ nanofibers maintained the high breakdown strength. Compared with single layer films, the extractable energy density was greatly enhanced in the sandwich-structured film. Instead of solely being stored at the interface between the dielectrics and the electrodes as in a conventional capacitor, charges are also stored at the additional interfaces between the two heterofilm layers within the multilayer dielectric nanocomposite. A numerical simulation was performed to solve the electrostatic equilibrium equation and then to obtain the scenario of charge storage at the hetero interfaces inside the nanocomposite.