The present investigation aims to develop activated flux for joining of DMR-249A steel using activated tungsten inert gas (A-TIG) welding process and characterize the fabricated weld joint. The various combinations of fluxes were prepared to decide suitable flux for DMR-249A steel. The design of experiment was carried out for optimization of welding parameters to achieve the desired depth of penetration. The square butt weld joints were fabricated on 10 mm thick plates employing A-TIG welding using developed flux and optimized process parameters employing double side welding procedure. The microstructural investigations and hardness, tensile and impact tests were carried out on the base metal and weld joint. The strengths, ductility and impact toughness of the joints were found to be comparable with that of the base metal.