The tungsten (W) inert gas (TIG) welding process that is applied with an active flux deposited on the workpiece surface just before welding is called activated flux TIG (A-TIG) welding. Layer deposition can be achieved by brushing or spraying over the surface, and welding is carried out after the surface dries out. This process has shown that it is possible to increase weld penetration and productivity up to three times higher or more compared with the TIG process in steels. In this review paper, A-TIG welding applications of steels were examined. The chemical composition and thickness of the flux and welding parameters (welding current, welding speed, arc length and shielding gas composition and its flow rate) affect the weld geometry. The activated flux welding mechanisms, effects of flux and welding parameters on weld geometry and microstructure and properties of A-TIG welds were explained.