Monodisperse, monocrystalline AuFe opticalmagnetic multifunctional nanocrystals were prepared by the nanoemulsion method using a copolymer surfactant. The structure and properties of the monocrystalline nanocrystals were analyzed by X-ray diffraction, transmission electron microscopy (TEM, including high-resolution TEM), selected-area electron diffraction, UV-vis spectroscopy, and vibration sampling magnetometry. The characterization shows the outstanding monodispersity and high monocrystallinity of the nanocrystals, which possess both well-defined optical and magnetic properties revealing broadband absorption with the surface plasmon resonance, peaking at~600 nm, and clear soft ferromagnetic behavior at room temperature. Such long-term stable, monocrystalline AuFe nanocrystals have novel optical and magnetic properties, which may offer exciting opportunities in fundamental studies and tremendous applications.