This work systematically investigates the effect of modifier polyvinylpyrrolidone (PVP) on the microstructure, dielectric and energy storage properties of BaTiO3/PVDF composites. The results demonstrate that the BaTiO3 nanoparticles modified by PVP are uniformly dispersed in the composites, and the defects including cracks and voids are obviously decreased in contrast to the composites with unmodified BaTiO3 nanoparticles. Due to the enhanced interfacial polarization, the composites with BaTiO3@PVP show improved dielectric properties compared with the composites with unmodified BaTiO3 nanoparticles. For instance, at 1 kHz, the dielectric constant and dielectric loss of the composite with 50 vol% of BaTiO3@PVP nanoparticles are 80.4 and 0.085, while of which the BaTiO3/PVDF are 35 and 0.265, respectively. The discharge energy density of the composites is largely improved with PVP engineered BaTiO3 nanoparticles. The composite with 30 vol% BaTiO3@PVP achieves a discharged energy density of 4.06 J/cc at 240 kV/mm, which is 116% larger than that of pure PVDF (1.88 J/cc). This research provides an effect modifier to prepare high performance dielectric materials.