We align the band edges of BiVO4 at the interface with liquid water by combining advanced electronic-structure calculations, molecular dynamics simulations, and a computational hydrogen electrode. After accounting for spin–orbit coupling and thermal and nuclear quantum motions, we achieve good agreement with experiment, particularly with one-shot GW calculations and semiempirically tuned hybrid functionals. The pH-dependent mechanism of the water oxidation reaction is discussed in consideration of the pH at the point of zero charge, the pKa of adsorbed water molecules, and the redox levels of the rate-determining step of the reaction. The mechanism pertaining to acidic conditions is found to dominate over a large pH range. The kinetically more favorable oxidation of hydroxyl ions is favored only in highly alkaline conditions and could be hampered by corrosion processes. Advanced electronic-structure methods are shown to be instrumental in overcoming the erroneous physical picture achieved at the semilocal level of theory.