New magnesium ion conducting polymer electrolyte films are developed and their experimental investigations are reported. The polymer electrolyte films are composed of various poly(vinylidene fluoride-co-hexafluoropropylene):magnesium trifluoromethanesulfonate compositions (PVdF-HFP:Mg(Tf)2 in weight ratio) with different quantities of 1-ethyl-3-methylimidazolium trifluoromethane-sulfonate ionic liquid (EMITf). X-ray diffraction reveals that the pristine PVdF-HFP polymer filmpossesses a semi-crystalline structure and its amorphicity increases with increasing Mg(Tf)2 and EMITf concentrations. From thermal analysis, the melting temperature (Tm), relative crystallinity (xc) and thermal stability of the 90PVdF-HFP:10Mg(Tf)2 gel polymer electrolyte film doped with 40 wt.% EMITf are obtained as 112 ℃, 21.8% and 355 8℃, respectively. The room-temperature ionic conductivity of the gel polymer electrolyte film increases with increasing EMITf concentration and reaches a high value of approximately 4.63 × 10-3 S cm-1 at 40 wt.% EMITf due to its amorphicity increase and interconnected pore structure. For the 40 wt.% EMITf electrolyte film, the temperature dependence of ionic conductivity follows the Arrhenius relation with an activation energy of 0.35 eV. The electrochemical stability window of the 40 wt.% EMITf electrolyte film is determined as ~4.8 V. The findings from this study are promising and have great potential for practical ionic device applications, particularly in rechargeable magnesium ion batteries.