In the present work, we reported the exploration of photoanodes based on mesoporous WO3 nanobelts through a foaming-assisted electrospinning strategy. The introduced polyvinylpyrrolidone in the raw solutions played a determining role on the formation of the nanobelts, enabling their fabrication in a controlled manner. The as-fabricated mesoporous WO3 nanobelts exhibited a photocurrent density of 311Acm(-2) and incident photon-to-current eciency of 6.5% at 350nm and 1.2V vs. Ag/AgCl under simulated sunlight illumination, which are 2.3 times to that of cylindrical nanofibers. Furthermore, our discovery confirmed that, in comparison to the conventionally cylindrical nanofibers, the nanobelts with a rectangular cross section could be a better candidate for constructing photoanodes with enhanced photoelectrochemical efficiency and stability.