By solution casting, solid polymer electrolytes complexed with magnesium trifluoromethanesulfonate (Mg(CF3SO3)2) and polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) at various concentrations were created. Electrochemical impedance spectroscopy is used to examine the conductivity and dielectric response of solid polymer electrolyte (SPE) systems at a temperature of 303–353 K and in the frequency range of 1Hz–10 MHz. The Vogel-Tamman-Fulcher equation effectively explains how ionic conductivity varies with temperature. A polymer electrolyte with 70% polymer and 30% salt was found to have the maximum conductivity at 303 K. The ionic conductivity enhances because of the enhancement of free ions with the raised salt content. At various temperatures, characteristics including complex electrical modulus (M*), complex permittivity (ε*), and frequency dependence of ionic conductivity (σ) have been studied. It is important to keep in mind that electrode polarization (EP) effects might cause the dielectric constant’s magnitude to be excessive at lower frequencies. Temperature increase has improved the dielectric permittivity and loss. The AC conductivity slightly deviates from the universal power law in the low-frequency zone under EP control.