Poly(vinylidene fluoride) with different contents (1–15 mass%) of clay minerals (kaolinite and halloysite) has been synthesized by solution-casting method to investigate the electroactive β-phase formation mechanism and the dielectric properties of the clay polymer nanocomposite (CPN) films. X-ray diffraction spectra, Fourier transform infrared spectroscopy, micro-Raman spectroscopy and differential scanning calorimetry confirmed the formation of electroactive β-phase in PVDF matrix after the addition of clay minerals. Field emission scanning electron microscope images showed interfacial interaction in CPN between the polymer matrix and the clay minerals resulting in enhanced electroactive β-phase nucleation and large dielectric constant of the CPN thin films.