This study investigates the electrical properties of polypropylene (PP) composites produced via melt-processing, incorporating varying concentrations of as-grown carbon nanofibers (CNFs). The electrical conductivity of PP/CNF composites exhibits a notable increase with the addition of CNFs, reaching approximately ~ 6×10^-6 S m^-1 for composites containing 3 wt.% CNFs [1]. In addition to electrical conductivity, the dielectric properties of PP/CNF composites were systematically analyzed. The results indicate a gradual increase in dielectric permittivity with CNF loading, reaching a maximum value of ~ 13 for composites with 3 wt.% CNFs at 1 MHz. This enhancement is primarily attributed to the development of interfacial polarization, also known as the Maxwell–Wagner–Sillars effect, which arises from the presence of conductive nanofibers within the insulating polymer matrix, significantly influencing charge distribution and dielectric behavior. Furthermore, the Cole–Cole model, applied through the electrical modulus formalism, is used to examine the influence of CNF content on the dielectric relaxation behavior and frequency-dependent response of the composites. The analysis reveals that incorporating CNFs increases the material's heterogeneity and relaxation dynamics while also prolonging relaxation times and modifying charge-transport mechanisms [2]. This work aims to enhance the fundamental understanding of the electrical behavior of polymer composites filled with as-grown CNFs synthesized via chemical vapor deposition (CVD) without thermal post-processing.