The present work deals with the preparation of magnetic acrylate terpolymer nanocomposite by emulsion polymerization. This nanocomposite was applied for the removal of diesel oil from artificial seawater by magnetic separation. Magnetic terpolymer nanocomposite was characterized by Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Specific surface area and pore size distribution were measured by the Brunauer-Emmett-Teller (BET) method. Contact angle (CA) measurement showed superhydrophobic properties of magnetic acrylate nanocomposite. Kinetics and isothermal studies indicate that oil sorption fits the second-order kinetic model and the Langmuir isotherm. Magnetic acrylate terpolymer can be regenerated for six cycles.