A fluorescent-magnetic YPxV1−xO4:Eu@GdPO4 core/shell nanostructure was prepared by a two-step method. The YPxV1−xO4:Eu core was synthesized using a hydrothermal method, and it exhibits strong photoluminescence with the effective doping of phosphorus (P) and europium (Eu) into a YVO4 matrix. The hydrothermal process provides a hydrophilic and fresh surface for coating GdPO4 shell. As YPxV1−xO4:Eu and GdPO4 have the similar unit cell parameters, YPxV1−xO4:Eu nanoparticles (NPs) were favorably coated by an epitaxial growth of GdPO4 shell in aqueous phase. The core/shell nanostructure was identified by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The GdPO4 shell not only possesses the paramagnetic character, but also enhances the photoluminescence efficiency by blocking the non-radiative de-excitation from the VO43−groups to the surface quenching sites. These optical and magnetic properties promise outstanding fluorescent-magnetic bifunctional nanomaterials.