Multifunctional nanostructures containing two or more different materials have received great interest in recent years because of their high prospects for applications as advanced nanomaterials. These nanocomposites exhibited innovative physical and chemical characteristics due to a controlled structure and interface interactions. These nanohybrids can exist in different forms such as core–shell, dimers, dumbbell shape, and Janus morphology systems and presented improved optical, magnetic, and catalytic properties. Gold–iron oxide nanostructures in hybrid form emerged as a 286promising class for enhanced applications, especially in the medical field where a single nanosystem can be used for multitherapy, for example, magnetic hyperthermia and plasmon thermotherapy. This type of nanostructure is usually obtained by physical deposition methods, but in recent years solution-phase chemical synthesis has also been applied for the formation of these bifunctional nanoparticles. In this chapter, we will review different properties of nanohybrids based on gold–iron oxide nanostructures and their applications in biological and medical fields.