The growing demand for biodegradable and sustainable materials has sparked an interest in composites based on natural polymers. Here, we present the development of thin biocomposite films made from carboxymethylcellulose, sodium alginate, and walnut shell-derived activated carbon. Activated carbon derived from walnut shells (ACWS) was prepared by chemical activating zinc chloride followed by thermally treating it further. Biocomposite films containing different amounts (0-2% by weight) of ACWS were characterized to determine how adding ACWS affects their structure, thermal properties, electrical properties, and surface morphology. Fourier-transform infrared spectrometry confirmed the presence of functional groups and that all three materials were compatible. According to thermogravimetric analysis, increasing concentrations of ACWS resulted in increased thermal stability with the greatest amount of ash (44.68%) occurring at 1 wt% of ACWS. The results from differential scanning calorimetry analysis did not indicate any significant differences in thermal transitions. Based on the results from electrical conductivity measurements, the highest conductivity was obtained with 0.5% by weight of ACWS. Scanning electron microscopy (SEM) imaging and energy dispersed X-ray spectroscopy (EDX) showed that the ACWS was homogeneously distributed and successfully incorporated into the polymer matrix. These findings suggest that ACWS is a potential additive to improve the performance of biodegradable films while also aiding in developing sustainable materials.