The effects of modes of metal transfer, i.e., short-circuit (SC) and spray (S) modes in single-pass gas metal arc welding of modified ferritic stainless steel using two types of austenitic stainless steel filler metals on microstructure as well as corrosion behavior of weld metal and high-temperature heat-affected zone (HTHAZ), were investigated. The results show that primary solidification modes (PSM) of the welds were exclusively dependent upon the Cr-eq/Ni-eq ratio of the respective welds. However, the amount of grain boundary austenite and martensite transformation in the welds were solely dependent upon the mode of metal transfer and the extent of cooling rate. Regarding the corrosion mechanism, grain boundary corrosion (GBC) behavior of welds and HTHAZ relied on the microstructural changes along the grain boundary due to the variation in mode of metal transfer. The results show that S-mode resisted grain boundary corrosion of the welds and both GBC as well as pitting corrosion of the HTHAZ. On the other hand, SC-mode improved only pitting corrosion resistance of the welds. Between the filler wires used, 316L welds, in general, provided better corrosion resistance compared with 308L welds.