A significant effect of the five major (121), (210), (111), (200), and (040) exposed facets obtained experimentally for orthorhombic α-SnWO4 material on its performance for photocatalytic water splitting is highlighted from a hybrid DFT-based comprehensive study. Their electronic, redox, and transport characteristics reveal significant anisotropic characters. The specific function of each surface in water oxidation and proton reduction is in direct relationship with the exposed W coordination number. Our study predicts the (210) facet as being the only possible good candidate for OER and HER upon surface modification, whereas the (200) facet is found a good candidate only for HER. The (121) facet is an acceptable candidate for both OER and HER and the (111) facet for HER only but less potentials than (210) and (200). The (040) facet is an unsuitable candidate neither for OER nor for HER. Interestingly, the proposed (001) facet is predicted to be the best candidate for HER. These results indicate the right direction to be followed for enhanced photocatalytic water splitting reactions based on a rational design of facet-oriented α-SnWO4 samples.