Nowadays, hexavalent chromium Cr (VI) loaded wastewater released from the leather tanning industry poses an increasing risk to human health and the environment. Currently, there are different conventional methods used to remove Cr (VI), however, they have different drawbacks like excess sludge production, treatment cost, and environmental pollution. There is a need for environmentally friendly and cost-effective methods for removal. Therefore, this study aimed to evaluate hexavalent chromium removal efficiency and capacity of chitosan-activated carbon nanocomposite from tannery wastewater. The nanoparticle was synthesized from an inedible part of the mushroom through demineralization, deproteinization,and deacetylation process. The nanoparticle was produced by the ionic gelation method used for the removal of hexavalent chromium from both synthetic and real wastewater. The particle size, functional groups, and thermal stability of nanoparticles and nanocomposite were characterized by XRD ,FT- IR, and TGA, respectively. The results revealed that the produced nanocomposite was with a particle size of 16.12 nm crystalline. The concentration of Cr (VI) was determined by using Carry UV-Visible spectroscopy. The adsorption study revealed that the optimum pH, contact time, initial concentration, agitation speed, and dose were 4, 90 min, 4 mg/l, 150 rpm, and 0.7 gram with an adsorption capacity of 26.8 mg/g respectively. The maximum adsorption efficiency of the adsorbent investigated via monolayer formation was determined to be 96.99% at the optimum parameters. The adsorption of Cr (VI) on the nanocomposite was best fitted to the Langmuir isotherm model (R2=0.998), While the kinetics of Cr (VI) adsorption on this adsorbent, was the most suitable to the pseudo-second-order model (R2= 0.999). The presented study proved that chitosan-activated carbon nanocomposite could be promising adsorbents for effective removal of hexavalent chromium from tannery wastewater treatment and conservation processes regarding improving environmental protection and community services.