The hetero‐bimetallic polyanionic compound BiCu2(TeO3)(SO4)(OH)3 was synthesized using hydrothermal techniques. Single‐crystal X‐ray diffraction analysis revealed that title compound crystallizes in the monoclinic space group P21/n (No. 14) with lattice parameters a = 9.5513(15), b = 6.3022(10), c = 13.955(2) Å, β = 102.845(3)°, and Z = 4. The structure of title compound is a three‐dimensional tunnel framework consisting of edge‐sharing two‐dimensional [Cu3O10]14– layers linked by BiO8bicapped trigonal prisms, TeO32– trigonal pyramids and SO42– tetrahedra. Along [010], each Cu(1)O6 octahedron shares two edges with adjacent Cu(1)O6 units to form infinite one‐dimensional zigzag chains, which are connected by double inverted Cu(2)O6 octahedral units via edge sharing (O9···O8). The suitability of crystal for optical applications was investigated by UV/Vis/NIR spectroscopy. Raman and FTIR spectra were used to confirm the presence of various functional groups such as TeO32–, SO42–, OH– in the crystals.