Ramie fabrics were modified with biobased electrolytes, i.e. cationic chitosan and anionic phytic acid, and the flame retardant cationic electrolyte melamine by a layer-by-layer (LbL) assembly method. Then, the LbL-modified fabric-reinforced unsaturated polyester resin (UPR) composites were fabricated by a hand lay-up method. The onset thermal degradation temperature of the LbL-modified fabric-reinforced UPR composites was lower than that of the raw fabric-reinforced UPR sample, while char residues of the composites were greatly improved and the release of combustible organic volatiles was suppressed during the combustion. Moreover, the flame retardancy of the composites was enhanced with increasing the LbL assembly number, which was evidenced by the markedly reduced peak heat release rate and the total heat release values obtained from cone calorimetric tests. The limiting oxygen index value of the composites was increased from 26.0% to 34.5%.