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 311 μA cm−2 and incident photon‐to‐current efficiency of 6.5 % at 350 nm and 1.2 V 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.