Inorganic/polymer nanocomposite films have attracted pronounced attention for electric energy storage applications since their high power energy density and fast charge-discharge ability. In this work, the flexible nanocomposite films composed by the paraelectric SiTiO3 nanofibers (ST NFs) and poly(vinylidene fluoride) (PVDF) were prepared by a solution cast method. The ST NFs, synthesized by an electrospinning method, were coated with a dense and robust dopamine layer which could effectively improve the filler-matrix distributional homogeneity and compatibility. The composite film with an optimized filler content illustrates a high discharge energy density of 9.12 J/cm(3) at 360 MV/m, which is about 625% over the biaxially oriented polypropylenes (BOPP) (1.2 J/cm(3) at 640 MV/m). Moreover, the composite film shows a superior power density of 2.31 MW/cm(3) and ultra-fast discharge speed of 178 ns. Therefore, the present approach might be extended to the fabrication of similar polymeric nanocomposites for high-performance capacitor energy storage devices.