A new family of quaternary mixed-framework chalcohalide semiconductors has been synthesized by conventional solid-state reactions in an intermediate temperature region of 400−430 °C. These include CdSbS2Cl (1), CdSbS2Br (2), CdBiS2Cl (3), CdBiS2Br (4), CdBiSe2Br (5), and CdBiSe2I (6). Single-crystal structure analyses of this compound series reveal two types of crystal structures depending upon the combination of chalcohalide anions, and they crystallize in an orthorhombic Pnma (type I) and monoclinic C2/m (type II) space group. Type I is adopted by two sulfochlorides, 1 and 3, and one selenobromide, 5. Type II is adopted by two sulfobromides, 2 and 4, and one selenoiodide, 6. Both structure types have slabs built of corner and edge shared Cd-centered CdQ6-xXx (Q = S, Se; X = Cl, Br, I; x = 0, 2, 4) octahedra that resemble the (110) plane of a distorted NaCl-type structure. In the type I structure, this slab contains only CdQ4X2 octahedra, while type II shows alternating CdQ6 and CdQ2X4 octahedra. In both structure types, each M3+ (M = Sb, Bi) cation of CdMQ2X forms a distorted square pyramid, MQ5, as found in M2Q3. The MQ5 unit is weakly coordinated to three X atoms to form a distorted bicapped trigonal prism, MQ5X3. In forming the extended network structure, the CdQ6-xXx and MQ5X3 units are solely linked through chalcogenide anions. The Fourier transform infrared spectroscopy studies suggest that these chalcohalides are transparent in the mid-IR region (1400−4000 cm-1). The UV−vis spectroscopy results in a band gap ranging from 1.3 to 2.2 eV, showing a red shift with respect to the corresponding binary chalcogenides CdQ. The results of tight-binding electronic band structure calculations suggest that the origin of this red shift is due to the lone-pair effects from Sb and Bi.