This study investigates the gas tungsten arc (GTA) weldability of austenitic stainless steel (STS) 304 using STS 308L and high-entropy alloy (HEA) fillers and its applicability in cryogenic environments. Because the grain sizes of both weld metals (WMs) were coarser than those of base metal (BM), and all WMs have a few phase transformations, the tensile properties of all WMs were worse than that of the BM. However, the tensile strength and elongation of HEA weld at 77 K increased simultaneously than those at 298 K, whereas the elongation of STS 308L weld decreased at 77 K than that at 298 K. All WMs exhibited excellent tensile strengths at 77 K, attributable to martensite transformations and deformation twins, respectively.