A zero valent iron-loaded nano-bentonite intercalated carboxymethyl chitosan (nZVI@nBent–CMC) composite was fabricated and characterized by FT-IR, TEM, TEM–EDX, XRD, BET surface area, and zeta potential measurements. The as-fabricated nZVI@nBent–CMC composite exhibited excellent removal efficiency for both anionic Congo red (CR) dye and cationic crystal violet (CV) dye. The maximum uptake capacities of CR and CV onto the nZVI@nBent–CMC composite were found to be 884.95 and 505.05 mg/g, respectively. The adsorption process of both dyes well fitted with the Langmuir isotherm model and pseudo-second order kinetic model. Thermodynamic data clarified that the adsorptions of both CR and CV onto the nZVI@nBent–CMC composite are spontaneous processes. Moreover, the adsorption of CR onto the nZVI@nBent–CMC composite was found to be an exothermic process while that of CV is an endothermic process. The nZVI@nBent–CMC composite also exhibited excellent reusability for both studied dyes without noticeable loss in the removal efficiency, suggesting its validity to remove both anionic and cationic dyes from wastewater.