A novel multifunctional microsphere with an iron oxide-improved mesoporous silica shell and a Fe₃O₄@SiO₂ core has been successfully prepared by a hydrothermal method and impregnation process. The resulting Fe₃O₄@nSiO₂@mSiO₂–Fe core–shell microspheres are utilized as a catalyst for the removal of 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) and its derivatives, i.e., 1,1-dichloro-2,2-bis(4-chlorophenyl) ethane (DDD) and 1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene (DDE). The results indicated that the iron oxide nanoparticles were well dispersed on the mesoporous silica shell of Fe₃O₄@nSiO₂@mSiO₂. DDT, DDD and DDE could be quickly and effectively removed from aqueous media in 60 min, and completely dechlorinated at 350 °C by Fe₃O₄@nSiO₂@mSiO₂–Fe. More importantly, the Fe₃O₄@nSiO₂@mSiO₂–Fe microspheres were superparamagnetic and could be separated and collected easily and rapidly using a magnet.