This study investigates the influence of gas tungsten arc welding (GTAW) current modes on dissimilar joints between Inconel 718 and AISI 410 martensitic stainless steel, targeting aerospace applications. Welding these alloys is challenging due to their differing thermal and chemical properties, which lead to brittle Laves phase formation, elemental segregation, and residual stresses. To address this, constant current (CCGTAW) and pulsed current (PCGTAW) techniques were compared. Microstructural characterisation was performed using optical and scanning electron microscopy to examine fusion zones, interfaces, and heat-affected zones. Both weldments showed niobium-rich Laves phases; however, PCGTAW resulted in a lower volume fraction (7.06%) than CCGTAW (10.50%), indicating improved suppression. Tensile failures occurred in the AISI 410 base metal for both welds. Microhardness profiles revealed uniform fusion zone hardness, softening in the IN 718 HAZ, and martensitic hardening in the AISI 410 HAZ. Hot corrosion tests at 650 °C in a K2SO4-NaCl environment showed superior resistance in PCGTAW welds, with lower weight gain, reduced oxide spallation, and a smaller parabolic rate constant (Kp). These enhancements are attributed to grain refinement, reduced segregation, and a narrower partially melted zone. Overall, PCGTAW significantly improves joint integrity and corrosion resistance, making it ideal for aerospace-grade dissimilar welding applications.