YVO4∶Eu fluorescent nanomaterials with small size and strong fluorescent intensity were synthesized via a hydrothermal method by using polyethylenimine (PEI) as the modifier, and the reaction mechanism of this synthesis was also discussed. The as-synthesized nanomaterials were characterized through transmission electron microscopy (TEM), X-ray diffraction (XRD) measurements, Fourier transform infrared (FT-IR) spectroscopy and fluorescence spectroscopy (FS). The as-prepared fluorescent nanomaterials were well-dispersed and spherical in shape with an average diameter of about 30 nm, which were modified with a layer of PEI on surfaces. The fluorescent nanomaterials were of pure tetragonal YVO4 structure. They could emit strong red fluorescence under the 254 nm ultraviolet excitation. The YVO4∶Eu fluorescent dry powders were then used as a novel fluorescent label for the development of latent fingerprints on various smooth substrates. Furthermore, the sensitivity and the resistance to background interference in fingerprint development were investigated in detail. The results showed that, use of YVO4∶Eu fluorescent nanomaterials to develop latent fingerprints resulted in clearly defined friction ridge details of fingerprints and eliminated background interference under 254 nm ultraviolet light. Compared with the traditionally used fluorescent developing powders, our YVO4∶Eu fluorescent nanomaterials were a novel agent for latent fingerprint development with high sensitivity, high contrast, and low background interference.