[en] Bismuth-based binary compounds, including Bi₂Se₃ and Bi₂Te₃, have attracted increasing attention as well-known topological insulators. On the other hand, bismuth-based ternary compounds exhibit diverse properties, such as, ultrahigh carrier mobility, and strong Rashba spin splitting. Moreover, they boast of superior photocatalytic properties, implying great potential to be used in a wide range of applications. The unique structure and properties of two-dimensional (2D) materials, especially the extraordinary electronic and optical properties of 2D Bi₂O₂Se, have given rise to significant research interests for the exploration of 2D bismuth-based ternary compounds. In this review, we will comprehensively discuss the properties of three important families of bismuth-based ternary compounds, including Bi₂O₂X (X = S, Se, Te), BiTeX (X = Cl, Br, I), and BiOX (X = Cl, Br, I). In particular, we have placed emphasis on the latest progress in their 2D forms, including their novel properties and applications. This review would aid in understanding the superior performance of bismuth-based ternary compounds and offer a perspective for future research on these emerging 2D materials. (topical review)