A novel spherical anatase TiO2 mesocrystal/SrTiO3 heterojunction with favored CrVI adsorption, bolstered charge carrier separation and well-preserved reduction capability was successfully produced, which exhibited enhanced activity toward photocatalytic reduction of CrVI. Display omitted •Spherical anatase mesocrystal/SrTiO3 nanodot type-II heterojunction was prepared.•Favored CrVI adsorption and bolstered charge carrier separation were realized.•The heterojunction showed remarkably enhanced photocatalytic reduction of CrVI. Mesoporous anatase TiO2 sphere based materials has long been the focus of intensive research dealing with environmental-related issues due to their significant advantages in terms of structural isotropy, high surface area, structural stability, and low cost. However, in most cases, the employed mesoporous anatase spheres were comprised of nanocrystalline subunits with random crystalline orientations, which means that numerous grain boundaries exist in the sphere-shaped particles, suppressing their performance in various applications. Herein, by using mesocrystalline anatase submicrospheres that were synthesized via utilizing SO42- ions to modulate the growth dynamics of anatase crystals in the green mixed solvents of PEG-400 and H2O as both template and reactant, novel sphere-shaped anatase mesocrystal/SrTiO3 nanodot heterostructures were successfully produced. These spherical anatase mesocrystal/SrTiO3 heterostructures exhibited noticeably enhanced activity toward reduction of hexavalent chromium (CrVI) under stimulated solar light irradiation, which was largely attributed to their favored adsorption of CrVI, bolstered photogenerated charge carrier separation and well-preserved reduction capability due to the construction of a well-defined type-II heterojunction with tight interfacial contacts and strong interactions. This work will be useful for the designed fabrication of micro/nanostructured TiO2 based photocatalysts with complex spherical morphologies for photocatalytic applications in environmental purification.