Various fillers (commercial, nipa palm, sisal activated carbon, zeolite) were incorporated with regenerated cellulose matrix that dissolved using lithium chloride/N, N-dimethylacetamide solution. The biosorbent films were successfully prepared via solution casting and then characterized by Fourier transform infrared spectrometer (FTIR), Xray Diffractometer (XRD), thermogravimetric analyzer (TGA), and scanning electron microscope (SEM). The biocomposite films with embedded commercial activated carbon exhibited the largest adsorption capacity of methylene blue (146.81mg g-1). Although the adsorption ability of the nipa palm and sisal activated carbon biocomposite was lower than the commercial activated carbon biosorbent film, both nipa palm and sisal activated carbon still could potentially be used as an alternative filler for cationic dye removal. On the contrary, zeolite had low adsorption efficiency owing to its morphology. The equilibrium adsorption experiment revealed that the Langmuir isotherm model best fitted the biocomposite films with commercial and sisal activated carbon, whereas the Freundlich adsorption model suited the biosorbent films with nipa palm activated carbon and zeolite than other models. The kinetics results of adsorption for all biocomposite films were well described using a pseudo-second-order kinetic model. The cellulose/activated carbon films would be promisingly utilized as a biosorbent for treatment of dye-contaminated wastewater.