A novel nanocomposite chitosan/montmorillonite has been prepared by using two different weight ratios of nano-montmorillonite (Chs1 and Chs2). The structure of the prepared adsorbents has been characterized by Fourier transform infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM). The adsorption kinetics and isotherm behaviors of Diamond Fast Brown KE (DFB) dye molecules onto prepared chitosan nanocomposites had been studied and compared using pseudo-first, pseudo-second, and Langmuir, Freundlich, Dubinin_Radushkevich models, respectively. The maximum adsorption capacities of DFB according to Langmuir isotherm model were 403.23 and 375.94 mg g-1 for Chs1 and Chs2, respectively. Moreover, our results indicate that the adsorption mechanism can be explained by the formation of the hydrogen bond. Based on the obtained results, Chs1 and Chs2 can be successfully applied for DFB dye removal from textile wastewater.