A novel pure cubic-phase pyrochlore structure tin(II) antimonate nanophotocatalyst, stoichiometric Sn2Sb2O7, has been prepared by a modified ion-exchange process using an antimonic acid precursor, and employed in visible-light-driven photocatalytic H2 evolution for the first time. The physicochemical properties (crystal phase, chemical composition and state, textural properties, and optical properties) of the material were investigated by different instrumental techniques. Compared with the antimonic acid precursor, the as-prepared Sn2Sb2O7 had a narrower bandgap, smaller crystal size, and larger BET surface area. The as-prepared Sn2Sb2O7 was validated as a promising candidate for visible-light-driven photocatalytic H2 evolution with a constant rate of 40.10 μmol·h−1·gcat −1.