In this study, bismuth vanadate (BiVO4) nanofibers were synthesized by hydrothermal method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and ultraviolet-visible absorption spectroscopy (UV-Vis) were used to study the crystal structure, morphology, optical and photocatalytic properties of the nanofibers. The XRD pattern revealed that the nanofibers were made with a pure monoclinic structure. The results of FTIR and EDS analyses showed that there were no impurity elements in the nanofibers. The FESEM image analysis revealed that the average length of the nanofibers was 0.208 μm. Using UV-Vis analysis, an optical gap of 2.19 eV was obtained, which is in the visible light range. The investigation of the photocatalytic activity of bismuth vanadate nanofibers in the photodegradation of Congo red dye showed that this type of bismuth vanadate nanostructure with a pure monoclinic structure is suitable for photocatalytic use and decomposition of organic materials with the help of sunlight.