The dissimilar welding of nuclear grade P91 and P92 steel was carried out using the shielded metal arc welding (SMAW) process. The dissimilar welded joint (DWJ) was subjected to mechanical and metallographic testing for as welded and post-weld heat treatment (PWHT) conditions. The SMAW joint was produced using the different filler composition (P91 filler and P92 filler). For the mechanical behavior of the DWJ, room temperature tensile tests, and Charpy toughness test was conducted for as welded and PWHT state. PWHT of the DWJ contributed a good amount of the ductility of the welded joint. The W and Mo-enriched P92 filler showed a higher tendency to unwanted δ ferrite phase formation as compared to the P91 filler. © 2021, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.