Glass formation was investigated for the Ga₂S₃–Sb₂S₃–CsX (X = Cl, Br, I) and Ga₂S₃–Sb₂S₃–AgCl systems. Glasses were obtained for the compositional regions that contain the parts of the lines from the eutectic point of the Ga₂S₃–Sb₂S₃ system (20GaS_3/2·80SbS_3/2) to the midpoint of the GaS_3/2–CsX system (50GaS_3/2·50CsX), extending to both sides of the lines. The glass transition temperatures were in the range of 210 to 280°C and tended to decrease with increases of the Sb₂S₃ and CsX contents. Some glasses in these systems had a temperature difference between crystallization and a glass transition of more than 200 K. The infrared transmission limits were located at approximately 14 µm, and the transmission range covered the atmospheric windows. These facts indicate that the glasses are suitable for use as optical materials in infrared optics. Furthermore, the absorption edges at the short wavelength side were blue-shifted, reaching the visible region with the incorporation of CsX. However, glasses in some compositional domains showed inhomogeneous structures in their matrices. Particularly, a unique morphology was observed the inhomogeneous CsCl-incorporated glasses, in which many voids of several micrometers in size were formed. The crystallization behaviors at the borders of the glass forming regions are discussed.