The mid-infrared (MIR) luminescent properties of Dy3+ ions in a new chalcohalide glass host, Ga2S3–Sb2S3–CsI, are investigated; and the suitability of the doped glass for MIR fiber lasers is evaluated. The Dy3+-doped chalcohalide glasses exhibit good thermal stability and intense MIR emissions around 2.96 μm and 4.41 μm. These emissions show quantum efficiencies (η) as high as～60％, and have relatively large stimulated emission cross sections (σem). The low phonon energy (～307 cm?1) of the host glass accounts for the intense MIR emissions, as well as the high η. These favorable thermal and emission properties make the Dy3+-doped Ga2S3–Sb2S3–CsI glasses promising materials for MIR fiber amplifiers or lasers.