Clay-based materials provide an efficient and environmentally benign strategy for heterogeneous catalytic oxidation. In this study, a novel Fe₃O₄-modified bentonite (Fe₃O₄-BT) catalyst was obtained by using the hydrothermal method. The catalyst was characterized by transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The Fe₃O₄ nanoparticles mainly existed on the surface and in the outermost pores of the BT, thus exhibiting improved dispersion and lower levels of aggregation. The catalytic activity of Fe₃O₄-BT was assessed in the degradation of methyl orange (MO) in the presence of H₂O₂. Fe₃O₄-BT showed higher MO degradation efficiency than both bare Fe₃O₄ and BT. The initial H₂O₂ concentration, catalyst loading, temperature, and initial pH were optimized for the degradation of MO. The MO decolorization rate was still ~90% after the Fe₃O₄-BT was reused five times. Additionally, the degree of ferric ion dissolution was only 3.23 × 10^-3 mg/L after 60 min. This novel catalyst was easily reclaimed by simple magnetic separation and exhibited good reusability and stability.