The aim of this study was to quantify the removal of halogenated pollutants (using triclosan as a model pollutant) from aqueous solution by zero-valent iron coupled with a weak magnetic field. We determined the removal efficiency of triclosan from a sodium sulfate solution at different pH values under both aerobic and anaerobic conditions. The removal of triclosan followed pseudo-first-order kinetics in both the presence and absence of a weak magnetic field. The calculated rate constants indicated higher removal efficiencies of triclosan under the aerobic condition compared to the anaerobic condition. In addition, increase of triclosan removal from acidic solutions was achieved with the assistance of weak magnetic field. X-ray diffraction and X-ray photoelectron spectroscopy analysis indicated that FeO(OH) and Fe3O4 were the main aerobic transformation products, suggesting that the zero-valent iron surfaces were completely oxidized. The aerobic and anaerobic transformation products of triclosan were analyzed by liquid chromatography tandem mass spectrometry. The results indicated that the application of a weak magnetic field could be an efficient and cheap treatment process to improve the removal of halogenated pollutants by zero-valent iron, which may be developed for future use.