A microwave-assisted method was developed to synthesize novel single-crystalline CuClSe₂ microribbons (MRs) in high yield. Their phase transformation and stability to thermal irradiation were systematically studied. The single CuClSe₂ MR-based device showed a favorable photosensitivity and long-term environmental stability. This implies good prospects for CuClSe₂ MRs in low-cost and high-performance photodetectors for practical use.