The Guar gum (GG)–lithium bis(trifluoromethanesulphonyl)imide (LiTFSI)-glycerol-based solid biopolymer electrolyte has been investigated. The polymer electrolytes has been prepared via solution casting technique and characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), 3D-laser profilometry and AC impedance studies. The amorphous nature and complexation has been revealed by XRD and FTIR. TGA reveals that the polymer electrolyte is stable up to 260°C. The average roughness was measured using 3D-laser profilometry. The ionic conductivity of the electrolyte was studied using impedance analysis. The best optimum ionic conductivity of 2.041 × 10−3 S cm−1 has been achieved for the film containing 60 wt% GG–40 wt% LiTFSI.