A facile two-step route is designed to synthesize chain-like Fe₃O₄@resorcinol-formaldehyde resins–Ag composite microstructures (denoted as Fe₃O₄@RF–Ag). Chain-like Fe₃O₄@RF microstructures are firstly obtained by the in situ polymerization of RF on Fe₃O₄ microspheres under the assistance of an external magnetic field; and then, Ag nanoparticles are strewn on the surface of the RF via in situ reduction by hydrazine hydrate. The as-obtained chain-like Fe₃O₄@RF–Ag microstructures are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), (high-resolution) transmission electron microscopy (HRTEM/TEM) and energy dispersive spectrometry (EDS). Experiments indicate that the as-prepared chain-like Fe₃O₄@RF–Ag microstructures can not only serve as outstanding antibacterial agents against bacteria including Staphylococcus aureus and Escherichia coli, but also as highly efficient catalysts for the hydrogenation of various compounds, including 4-nitrophenol, methylene blue and Rhodamine B. Also, the as-prepared chain-like Fe₃O₄@RF–Ag microstructures can be conveniently regenerated under extra magnetic field due to the presence of Fe₃O₄ and they show good cyclic stability, which is important for practical applications.