In this study, β-cyclodextrin was functionalized with [3-(2,3-epoxypropoxy)propyl]trimethoxysilane to obtain a new silica-based β-cyclodextrin in order to provide a binding side for immobilization onto iron oxide magnetic nanoparticles (MNPs). The prepared β-cyclodextrin-immobilized MNPs were characterized by a combination of Fourier Transform Infrared Spectroscopy, transmission electron microscopy, elemental analyses, and X-ray diffraction analysis. Moreover, the study regarding the removal of carcinogenic azo dyes such as Direct Blue 15, Evans Blue, and Chicago Sky Blue from aqueous solutions was also carried out using β-cyclodextrin-immobilized MNPs in a solid–liquid sorption system. The results indicate that the prepared β-cyclodextrin-based magnetic sorbent has high sorption ability towards Direct Blue 15, Evans Blue, and Chicago Sky Blue with ~98, 99, and 99 % at pH 3.0, respectively.