Activated flux assisted tungsten inert gas (TIG) welding of austenitic 316L stainless steel was investigated. Autogenous TIG welding was used to produce a bead-on-plate weld. The FeO, FeS, and FeF2 were selected as the flux powders. The results showed that the FeS and FeO fluxes produced high aspect ratio welds, while the FeF2 flux produced a relatively low aspect ratio weld. The undercut defect was produced with use of the FeS flux. An experimental result suggested the constriction of arc column as a mechanism in improving activated TIG penetration. In addition, activated TIG process can increase the delta-ferrite content in austenitic stainless steel weld metal.