A magnetic dye affinity adsorbent was prepared by coating the magnetic nanoparticles (MNPs) with chitosan (CS), which significantly decreased the non-specifically adsorbing protein. Following this, Reactive Red 120 (Red 120), chosen as a dye affinity ligand, was immobilized onto the chitosan-coated magnetic nanoparticles (CS-MNPs) to obtain the specific protein adsorption. The prepared functionalized adsorbents were characterized by SEM, FTIR, XRD, VSM, and elementary analysis. Factors influencing the adsorption of bromelain, e.g., initial protein concentration, medium pH, and ionic strength were investigated. The adsorption isotherm fitted the Freundlich model well. The regeneration experiment showed that the affinity superparamagnetic particles were suitable for bromelain adsorption.