<p>This work aimed to develop multifunctional sustainable fabrics with enhanced electrical conductivity, thermal resistance, and flame retardancy. The natural flax fabrics were chemically modified by in situ graft oxidative copolymerization of aniline and melamine to achieve the conductive and flame-retardant fabrics. Indeed, it has been tried to modify the surface of the fabrics through covalent bonding to increase the durability of the obtained properties. The process went through the following steps to achieve this goal. First, the flax fabric was treated with hexamethylene di-isocyanate in such a way that there are free isocyanate groups on the flax fabric surface. Then, the free isocyanate groups were further reacted with <i>p</i>-phenylenediamine to form an aminated flax fabric. The aminated flax fabric under went in situ oxidative graft copolymerization of aniline and melamine to form poly(aniline–<i>co</i>-melamine) grafted fibers as conductive textiles. In the preparation of grafted conductive textile, various molar ratios of aniline to melamine in the copolymerization feed and various weight ratios of poly(aniline–<i>co</i>-melamine) to flax fabric were applied. The synthesized fibers were characterized by various techniques, such as Fourier transform infrared, thermogravimetric analysis, X-ray diffraction, and pyrolysis-combustion flow calorimetry techniques. In addition, the synthesized fibers were studied by scanning electron microscopy analysis and this analysis confirmed the change in the morphology of the flax fabric surface. The TGA analysis showed that the thermal stability of the modified flax fabric was enhanced.</p> Graphical abstract <p></p>