Ultrathin BiVO₄ nanobelts with about 3 nm thickness have been firstly fabricated by a hydrothermal method. It has been discovered that these special nanostructures exhibit much higher photoelectric conversion efficiency as well as water splitting ability than commercial BiVO₄ nanoparticles. It is believed that the one-dimensional ultrathin structure of BiVO₄ nanobelts is of benefit for the separation and transmission of photoexcited electrons due to its short charge transfer pathway and favourable crystalline structure.