GeSe2–Ga2Se3–CsI chalcohalide glasses are synthesized, and their optical properties and thermo‐mechanical properties are studied. A typical characteristic of the glasses is their excellent transparency in the red‐light region in addition to the 8–14 μm atmospheric window, which is of vital importance to the quality control of infrared systems. The short‐wavelength absorption edge λs of the glass system has a distinct blue shift with increasing CsI content, and the physicochemical interpretations are suggested and formulated. These glasses present a glass transition temperature (Tg) around 300°C and good thermal stability. Consequently, they can be promising candidate materials for infrared optics, although their hardness is relatively weak.