Metal nanoparticles have been combined with magnet metal–organic frameworks (MOFs) to afford new materials that demonstrate an efficient catalytic degradation, high stability, and excellent reusability in areas of catalysis because of their exceptionally high surface areas and structural diversity. Magnetic Mx Oy @N-C (M = Fe, Co, Mn) nanocrystals were formed on nitrogen-doped carbon surface by using 8-hydroxyquinoline as a C/N precursor. The Co@N-C, MnO@N-C, and Fe/Fe2O3@N-C catalysts were characterized by X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), N2 adsorption/desorption, and X-ray photoelectron spectroscopy (XPS). The catalytic performances of catalysts were thoroughly investigated in the oxidation of aniline solution based on sulfate radicals (SO4−.) toward Fenton-like reaction. Magnetic Mx Oy @N-C exhibits an unexpectedly high catalytic activity in the degradation of aniline in water. A high magnetic Mx Oy @N-C catalytic activity was observed after the evaluation by aniline degradation in water. Aniline degradation was found to follow the first-order kinetics, and as a result, various metals significantly affected the structures and performances of the catalysts, and their catalytic activity followed the order of Co > Mn > Fe. The nanoparticles displayed good magnetic separation under the magnetic field.