We reported a simple protocol for synthesizing small-scale gold coated superparamagnetic iron oxide nanoparticles (SPION). The synthesis of the core-shell nanoparticles of the SPION-gold nanoparticles (GNP) was through chemical reduction method in an ultrasonic field environment. The SPION was produced by co-precipitating iron (ii) and (iii) chloride salt in sodium chloride solution as a c o-precipitating agent. The surface of the SPION was sonochemically functionalized with a 3-aminopropyltriethoxysilane (APTES) which served as a linker. Gold precursor was chemically reduced with chilled sodium borohydride in the presence of the APTES functionalized SPION seed. The GNP covalently binds and assembles on the terminal amine groups on the SPION. Physical characterization with Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction pattern (XRD) and Ultraviolet–visible spectroscopy (UV-Vis) confirmed the composite nanoparticles to be GNP coated SPION.