Cotton fabrics with single-faced flame resistance are successfully fabricated through a simple mist copolymerization process using pentabromobenzyl acrylate (PBBA) as the functional monomer. The co-monomers are methyl acrylate (MA), which can react with the hydroxyl groups of cellulose by transesterification, and divinyl benzene (DVB), a cross-linker. SEM images indicate that a very thin copolymer layer (the thickness is about 200 nm) was formed on the cotton fiber surface and the flame resistance tests show that the modified fabrics have an improved flammability with longer time to ignition (TTI), lower peak heat release rate (PHRR), lower total heat release (THR), and lower average mass loss rate (AMLR), when compared to the original cotton fabric. The modification also results in good wearing durability because the flame-retardant coating was covalently linked to the cotton fabric surface by many ester groups. Moreover, desired cotton characteristics such as tensile strength, water absorbency, vapor permeability and flexibility are mostly retained because the mist method gives a single-faced modification of the cotton fabrics.