A novel magnetic composite bioadsorbent composed of chitosan wrapping magnetic nanosized γ-Fe₂O₃ and multi-walled carbon nanotubes (m-CS/γ-Fe₂O₃/MWCNTs) was prepared under relative mild conditions and was characterized. Adsorption of methyl orange (MO) onto m-CS/γ-Fe₂O₃/MWCNTs was investigated with respect to pH, initial MO concentration, coexisting anions and temperature. Results of characterizations indicated that magnetic nanosized γ-Fe₂O₃ and MWCNTs have been wrapped by crosslinked chitosan. Introduction of MWCNTs could obviously increase the adsorption capacity (qe ) of MO onto bioadsorbent by 2.2 times. Kinetics data and adsorption isotherm were better fitted by pseudo-second-order kinetic model and by Langmuir isotherm, respectively. Values of activation parameters such as free energy (△G°), enthalpy (△H°) and entropy (ΔS°) were determined as 3.15-3.78kJmol⁻¹, −9.94kJmol⁻¹ and −20.65Jmol⁻¹ k⁻¹, respectively, indicating that the adsorption was feasible, spontaneous and exothermic process in nature. After adsorption, m-CS/γ-Fe₂O₃/MWCNTs could be effectively and fleetly separated by applying a magnetic field.