Hierarchical SnIn4S8 microspheres were successfully fabricated via a solvothermal method without the assistance of any templates or surfactants. These microspheres were of a new tetragonal polymorph, distinct from the cubic counterpart popularly reported in the literature. Systematic characterization indicated that these microspheres exhibited a diameter of 2–4 μm and were assembled by numerous interconnected nanosheets of 40 nm thickness. The formation mechanism of hierarchical SnIn4S8 microspheres was proposed by taking into account the influences of experimental conditions on the morphology and structure. Hierarchical microspheres possessed a large specific surface area of 197 m2 g−1 and an accessible porous configuration, which gave rise to an excellent visible light-driven photocatalytic efficiency for methyl orange degradation in aqueous solutions, superior to that for the known N-doped TiO2 photocatalyst.