<p>In this study, the microstructural evolution, mechanical properties, and corrosion behavior of tungsten inert gas (TIG)-welded dissimilar joints (DJs) between Nimonic 75 superalloy and Nitronic 50 austenitic stainless steel were investigated using three welding approaches: autogenous welding (DJ1), welding with a Ni-interlayer (DJ2), and welding with ERNiCrMo-4 filler metal (DJ3). Microstructural analysis revealed that the autogenous weld exhibited predominantly cellular and columnar dendritic structures, whereas the incorporation of a Ni-interlayer and ERNiCrMo-4 filler promoted the formation of finer equiaxed dendritic morphologies. Energy-dispersive spectroscopy of the interdendritic regions in the autogenous weld indicated Ti- and N-rich precipitates, suggesting the possible formation of Ti-rich carbides and/or nitrides. The addition of Mo and Cr through the ERNiCrMo-4 filler enhanced the tendency for carbide formation in the weld metal. Mechanical testing showed that the Ni-interlayer joint exhibited the highest ultimate tensile strength (~714.33 ± 6.03&#xa0;MPa), followed by the ERNiCrMo-4 filler joint (~697.33 ± 7.51&#xa0;MPa) and the autogenous joint (~636.67 ± 4.16&#xa0;MPa). Corrosion studies further demonstrated that the Ni-interlayer weld possessed the lowest corrosion current density (<i>i</i>_corr ≈ 0.43&#xa0;<i>μ</i>A/cm²), indicating superior corrosion resistance compared with the ERNiCrMo-4 filler weld (<i>i</i>_corr ≈ 3.27&#xa0;<i>μ</i>A/cm²) and the autogenous weld (<i>i</i>_corr ≈ 4.51&#xa0;<i>μ</i>A/cm²). The improved performance of the Ni-interlayer joint is attributed to its refined microstructure, reduced segregation, and enhanced compositional homogeneity across the weld region.</p>