The object of this study was to evaluate the discolorization efficiency of sunset yellow (SY) anionic dye from aqueous solutions by using new noble metal /Fe3O4 nanoparticles anchored on nanocellulose. Ag/Fe3O4@PEI nanoparticles (NPs) were synthesized through a solvothermal method. The prepared magnetic nanoparticles were added to nanocellulose dispersion to obtain Ag/Fe3O4@PEI/CNCs nanocomposite by the self-assembled method. The discolorization process, of SY dye, by Ag/Fe3O4@PEI/CNCs nanocomposite, was investigated in the time. The small amount of this nanocomposite (5 mg) is applicable for the removal of high concentrations of SY dye in 8 min. The nanocomposite showed high stability for the 5th cycle of the discolorization reaction.