This study evaluates the compatibility of dissimilar welding between Inconel 59 and Austenitic Stainless Steel (AISI 904L) using CO₂ Laser Beam Welding. The investigation includes macro and microstructure analysis, mechanical property evaluation, and the effects of cryogenic treatment. Weld geometry was assessed macroscopically, confirming process feasibility. Microscopic analysis revealed fine equiaxed dendrites in the fusion zone with minimal secondary phase formation. XRD phase analysis confirmed phase stability, while residual stress analysis indicated reduced tensile stress in the fusion zone and compressive stress in adjacent regions. The fusion zone exhibited an average hardness of 236 HV, attributed to the refined dendritic structure. Cryogenic treatment improved weld performance, with tensile strength increasing by 5.5 % in shallow mode and 15.3 % in deep mode, alongside a 4.6 % enhancement in impact strength in deep cryogenic conditions. These results validate the feasibility of dissimilar welding between Alloy 59 and AISI 904L for applications requiring high strength and temperature resistance.