Abstract: Two-dimensional materials have demonstrated significant potential in high-performance optoelectronic devices due to their ultra-thin thickness, high carrier mobility, and high integration density. Among them, bismuth-based oxyselenide Bi₂O₂Se is an emerging two-dimensional semiconductor material that exhibits very high electron mobility, a moderate bandgap, good flexibility, near-ideal subthreshold swing, and excellent environmental stability. These unique properties make it a promising candidate for applications in the field of optoelectronics. This paper provides a systematic overview of the crystal structure, electronic band structure, and synthesis methods of two-dimensional Bi₂O₂Se, as well as the relationship between its structure and fundamental properties. It also reviews recent important applications of Bi₂O₂Se in optoelectronics, including photodetectors, field-effect transistors, optical switches, and photocatalysis. Finally, the paper discusses existing challenges in the research of this material system, such as large-scale synthesis, device integration, surface defects, and interface studies, and prospects its important role in next-generation electronic devices and industrial applications.