Hybrid magnetic/plasmonic nanoparticles possess properties originating from each individual material. Such properties are beneficial for biological applications including bio-imaging, targeted drug delivery, in vivo diagnosis and therapy. Limitations regarding their stability and toxicity, however, challenge their safe use. Here, the one-step flame synthesis of composite SiO2-coated Ag/Fe2O3 nanoparticles is demonstrated. The hermetic SiO2 coating does not influence the morphology, the superparamagnetic properties of the iron oxide particles and the plasmonic optical properties of the silver particles. Therefore, the hybrid SiO2-coated Ag/Fe2O3 nanoparticles exhibit desired properties for their employment in bio-applications.