The effect of over-alloyed Ni-rich fillers on the weld mechanical properties of AISI 904L and Inconel 625 dissimilar joints achieved by pulsating current approach in gas tungsten arc welding (GTAW) is analysed in the present investigation. Micro-segregation and the migrated grain boundaries are noticed on the jointed zones of ERNiCrMo-4 and ERNiCrCoMo-1 respectively. The columnar dendrites near to the fusion line and the fine equiaxed dendritic structures at the centreline are witnessed in the weld regions of both the joints. Tension failures have occurred in the AISI 904L base metal. The notch tension test inferred that the weld strength is higher than the weak parent metal (AISI 904L). The impact toughness was considerably declined sharply compared to the parent metals. The notch tension and impact tests recommend the use of ERNiCrMo-4 filler for joining these dissimilar metals. The research findings based on the relationship between structure-property drawn from this investigation can be employed in the industries requiring the use of the novel joints. © 2019 IOP Publishing Ltd.