Nowadays, water pollution by industrial waste water that contains heavy metal elements, such as Cd, has become an urgent concern to be solved. In this work, magnetic γ-Fe2O3/Fe-doped hydroxyapatite (HAP) nanostructures are realized as Cd(II) adsorbents with outstanding adsorption performance. The Vibrating Sample Magnetometer (VSM) analysis and magnetic separation experiments reveal that γ-Fe2O3/Fe-doped HAP nanostructures can be effectively separated by external magnet. Compared with pure HAP, the γ-Fe2O3/Fe-doped HAP nanostructures show higher adsorbed concentration and adsorption rate. The maximum adsorbed concentration at the equilibrium is 258 mg g−1 (under initial concentration of 500 mg L−1, temperature = 25 °C and pH = 5.0), which is higher than values reported for most of HAP-based adsorbents. The adsorption data could be well fitted by the Freundlich model, and the adsorption kinetic follows the pseudo-second-order model. Furthermore, the study of adsorption mechanism reveals that both ion-exchange and electrostatic interaction are involved in process of Cd(II) adsorption.