Today, research is increasingly focused on surface control of semiconductors; however, very little is known about the effect of bulk chemical bonds on photoelectrochemistry properties. In this report, Bi2O(OH)2SO4 with and without specific Bi-O-S bonds (WB and WOB) is synthesized via hydrothermal and water bath methods, respectively, and we reveal the Bi-O-S bond-dependent photoelectrochemistry properties. Both WB and WOB belong to a monoclinic space group (P21/c), but the newly synthesized WB has different unit cell parameters of a = 8.062 Å, b = 8.384 Å, and c = 5.881 Å, compared with WOB (a = 7.692(3) Å, b = 13.87(1) Å, c = 5.688(2) Å). Compared with WOB (4.18 eV), WB has a narrower band gap (3.6 eV), higher electrical conductivity, and an increased charge separation efficiency. It is found that the electrons are easy to transfer along the newly formed Bi-O-S bond in bulk; thus, the Bi-O-S bonds in WB have efficiently improved the photoelectrochemistry properties. As a result, WB exhibits a 1.1 times higher photocatalytic activity than WOB for the degradation of RhB under ultraviolet light irradiation (<420 nm). This helps us to understand the photoelectrochemistry properties from crystal bulk, but not merely from the crystal surface; thus, this study provides a new idea for improved photoelectrochemistry properties of semiconductors.