Herein, a magnetically separable Fe3O4 decorated chitosan was facilely synthesized, systematically characterized, and subsequently employed as a versatile adsorbing material for the adsorption of malachite green and methylene blue dyes. The prepared adsorbent was characteristically examined through Fourier transform infra-red microscopy, scanning electron microscopy with energy-dispersive X-ray analysis, transmission electron microscopy X-ray diffraction, Brunauere-Emmette-Teller surface area analysis, thermogravimetric analysis, and vibrating-sample magnetometry techniques. The performance of adsorbent was studied in batch mode and the the time-dependent experimental data were analyzed with different kinetic models, and pseudo-IInd-order was provided the best fit for the adsorption of both the dyes with a high value of the regression coefficient. The adsorption equilibrium data of both the dyes was best explained by Langmuir isotherm, and the maximum sorption capacity of MG and MB was found to be 55.86 and 76.34 mg g-1, respectively. Thermodynamic analysis declared that the adsorption of MG and MB onto the MChi was endothermic and spontaneous in nature. Moreover, the adsorbent presented good reusability up to three successive ad-/de-sorption cycles, indicating that MChi is a promising applicant for the treatment of dye-containing wastewater.