Two ionic liquids, [BMIM][BF4] and [EMIM][BF4], have been used for the first time to synthesize ordered and well-defined WO3 nanoplates by electrochemical anodization. Different amounts of these ionic liquids have been added to the electrolytes and their influence on the morphological, structural and photoelectrocatalytic properties of the WO3 nanoplates has been extensively studied. The resulted nanostructures, especially those synthesized in the presence of 5%–10% ionic liquids, showed excellent photoelectrocatalytic performances under irradiation, due to their better morphology, size and arrangement. These results confirm the potentiality of ionic liquids, such as [BMIM][BF4] and [EMIM][BF4], in the synthesis by anodization of high-efficiency photoelectrocatalysts, which could be used in the energy and environmental fields.