Nanodielectric materials have been extensively studied because of their potential applications in energy conversion and storage systems. However, dielectric materials with high constant, low loss, and high toughness have yet to be developed. In this work, we design and fabricate different core-shell-structured hybrids composed of polymerized imidazolium ionic liquid (PIL) and carbon nanotubes (CNTs). The hybrids exhibit varied structure and coating layer thickness upon adjusting the concentrations of monomer and solvent and is used to fabricate nanodielectric composites. The polymer shell is formed as a part of the composite interface and thus directly alters the interfacial structure. The obtained composites exhibit varied dielectric behaviors over a wide frequency range. The dielectric properties of the composites can be easily tailored by choosing appropriate hybrids and controlling the proportion of fillers. These features render PIL-CNTs/PVDF as a potential high-performance dielectric material for applications in capacitors.