Hierarchical BiVO4 microspheres assembled by nanosheets were synthesized by hydrothermal process under microwave irradiation. The morphology and compositional characteristics of the BiVO4 architectures were investigated by SEM, TEM, and XRD. The possible formation mechanism for the architectures was discussed. UV–vis diffuse reflectance spectra indicated the BiVO4 hierarchical microspheres had absorption in both UV and vis light areas. The specific surface area and porosity of the BiVO4 architectures were investigated by using nitrogen adsorption and desorption isotherms. Because of the narrow bandgap and the novel micro-/nanostructure, the BiVO4 architectures show a more excellent photocatalytic activity under visible light irradiation than the BiVO4 solid microspheres and P25. Several possible reasons for the higher photocatalytic activity have been taken into consideration, namely, high specific surface area, hierarchical mesoporous structure, and quantum size effect. In addition, the photocatalyst is stable during the reaction and can be used repeatedly.