Bi⁵⁺ doped Bi₂WO₆ nanoflowers were prepared for the first time by hydrothermal method using sodium bismuth and sodium tungstate as raw materials. The crystal structure, micromorphology, optical absorption and photoelectrochemical properties of the materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV–vis spectrum, photocurrent response and electrochemical impedance spectroscopy plots. Using the degradation of Rhodamine B (RhB) under visible light as the reaction model, the effects of Bi⁵⁺ doping on the photocatalytic activity of Bi₂WO₆ nanoflowers were investigated. The results showed that Bi⁵⁺ doping reduces the bandgap of Bi₂WO₆ nanoflowers, and improves the absorption ability of Bi₂WO₆ nanoflowers in the visible-light region remarkably. The photocatalytic activity of Bi⁵⁺ doped Bi₂WO₆ nanoflowers was promoted significantly, and the degradation efficiency of RhB can reach 96% in 60 min under visible-light irradiation.