<p>Gel polymer electrolytes (GPEs) have gained attention as safer alternatives to volatile liquid electrolytes in electrochemical systems typically in dye-sensitized solar cells (DSSCs). However, their performance is limited by their high polymer crystallinity and low ionic conductivity. In this study, a series of polyvinyl alcohol (PVA)-based GPEs system were synthesized using potassium iodide (KI) salt in ethylene carbonate (EC), propylene carbonate (PC), and dimethyl sulfoxide (DMSO) solvent. Various concentrations of carbon black (CB) nanofillers were added in electrolytes to study the effect of nanofiller on electrolyte characteristics. The structural and electrochemical properties of the GPEs was systematically investigated using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and electrochemical impedance spectroscopy (EIS). XRD results confirmed a reduction in crystallinity with increasing CB content, while FTIR analysis indicated strong interactions between CB and the polymer matrix. The highest ionic conductivity across all samples was 15.90 mS cm⁻¹ for the PVA-based electrolyte without CB. Within the CB-doped series, conductivity increased with increasing of CB amount and reached a maximum of 11.80 mS cm⁻¹ at 12 wt% CB, indicating that moderate CB loading capable to form partially percolated networks that improve ion transport relative to other CB-containing samples. The findings demonstrate that carbon black able to tune the structural and electrochemical properties of PVA-based GPEs, although the GPE without CB gave the highest absolute conductivity in this study, offering promising potential for advanced electrochemical applications.</p>