The Cút glutinous rice, a traditional specialty of Quang Ngai province, is characterized by a long growth cycle and its adaptation to mineral-rich, hot water swamp ecosystems. However, the Cút glutinous rice in the production is degenerating in recent years. To accelerate the selection process and preserve this valuable variety, SDS-PAGE protein electrophoresis was applied to identify grains with low amylose and high protein content. Selection was based on the color intensity of waxy and α-glutelin protein bands. Field and laboratory assessments confirmed the successful purification of the Cút glutinous rice with the following characteristic traits: Plant height of 119.1–121.8 cm, panicle length of 27.8–28.6 cm, 7.8–8.7 panicles per clump, 1,000-grain weight of 25.1–25.6 g, and actual yield of 35–38 quintals/ha. The grain exhibits low amylose content (1.82–1.92%) and relatively high protein content (7.08–7.36%). It also shows mild susceptibility to blast, silver leaf, brown leaf blight, and leaf roller diseases, while demonstrating strong resistance to brown spot and brown planthopper. This research makes a significant contribution to the conservation, exploitation and development of the local specialty Cút glutinous rice variety in Quang Ngai province.