Abstract: Flame retardancy is a key performance for reducing fire casualties and property damage. However, traditional flame retardants often cause a decrease in material mechanical properties, along with hazards such as toxic gas release and bioaccumulation, severely limiting their applications. Carbon dots, as an emerging multifunctional carbon nanomaterial, have outstanding advantages such as excellent dispersibility, good thermal stability, wide raw material sources, environmental friendliness, and good biocompatibility. The new nanocomposite materials constructed by carbon dots have shown promising potential for practical applications in the field of polymer fireproofing. This article reviews the research progress on the flame retardant mechanism and application of carbon dots and their composite materials. Firstly, the main factors affecting the flame retardancy of carbon dots are analyzed on the basis of summarizing the flame retardant mechanism of carbon dots. In addition, the flame retardant applications of modified carbon dots in materials such as epoxy resin, polyvinyl alcohol, and cotton textiles are introduced. Finally, the development direction of modification technology and functionalization strategy for carbon dot flame retardants is discussed, providing theoretical reference and design ideas for the development of efficient, low toxicity, and environmentally friendly polymer-carbon dot flame retardant composite materials.