AbstractSummary: Styrene‐butyl acrylate copolymer (St‐BA)/graphite oxide (GO) nanocomposites and St‐BA/GO/MPP [melamine poly(metaphosphate)] composites were prepared via an intercalation process by the ball‐milling method and characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microanalyzer (SEM). Cone calorimetry experiments were carried out to evaluate their flammability. The cone calorimetry data suggested that the addition of GO can decrease the heat release rate of St‐BA copolymers significantly. Furthermore, there was also a synergistic effect on the fire retardant property by the combination of GO and MPP. However, no prominent effect of the GO content on the reduction of peak heat release rate (HRR) in nanocomposites could be found.SEM image of the fractured surface of St‐BA/GO/MPP hybrid.imageSEM image of the fractured surface of St‐BA/GO/MPP hybrid.