A facile synthetic route under mild conditions to the preparation of gold nanostars (GNSs) with Fe₃O₄ cores (Fe₃O₄@GNSs), possessing magnetization and tunable optical properties from the visible to near-infrared (NIR) region, was developed. Additionally, the resulting Fe₃O₄@GNSs described here show good catalytic activity for the reduction of potassium ferricyanide as a model reaction. Importantly, the catalyst, Fe₃O₄@GNSs, can be easily recycled with an external magnet and exhibits long-life, good reusability and stability. We also anticipated that Fe₃O₄@GNSs may provide a platform for broad potential diagnostic and therapeutic biomedical applications due to its magnetization and tunable optical properties from the visible to NIR region.