The optimal process parameters of CO2 laser welding were arrived out at performing iterative experimentation with different speeds for Ni-based super alloy Inconel 718 and re-sulphurized martensitic grade stainless steel, AISI 416. Microscopy investigations corroborated the micro-segregation of Laves phase augmented in Nb at the fusion zone of CO2 laser welds and also trivial liquation cracks or micro fissuring at the heat affected zone (HAZ) of Inconel 718 were observed. The fusion zone microstructure attested the absence of solidification cracks and/or porosity. Tensile failures were observed on the weaker parent metal of AISI 416, despite some minor microstructural deficits in the fusion zone. The current work attests that dissimilar joints of Inconel 718 and AISI 416 could be obtained in a single pass using keyhole mode CO2 laser welding process.