Activated carbon/bentonite/magnetite nanobiocomposite was used to remove Cr(VI) ions from water. The physical properties of the nanocomposite were characterized by various spectroscopic analyses. The specific surface area of the nanocomposite was 337.96 m2g−1, which is a significant value. The maximum uptake efficiency and maximum uptake capacity of the adsorbent were 98 % and 29.32 mg g−1, respectively, which are also considerable values. The maximum uptake efficiency was obtained at pH 9, after 80 min, at a nanocomposite dosage of 2 g L−1, an ion concentration of 5 mg L−1, and a temperature of 25 °C. The thermodynamic study indicated that the sorption process was spontaneous and exothermic. The nanocomposite reusability study after six cycles of reuse demonstrated that the bionanocomposite can be used for up to three cycles without significant change in its uptake efficiency.