<p>Pulsed Tungsten Inert Gas (PTIG) welding of aluminium joints generates flaws such as porosity, hot cracking, and a coarse grain structure. Friction stir processing (FSP) reduces flaws such as weld discontinuities and microcracks and improves grain refinement. Hence, the present work examines how the mechanical properties of joints between the dissimilar aluminium alloys AA5083 and AA6082 are improved by FSP. The current work shows the use of FSP as a post-weld treatment to enhance microstructure and mechanical properties of PTIG-welded dissimilar AA5083/AA6082 joints through dynamic recrystallisation and grain refinement. The FSP was carried out using a straight tool pin profile at a tool rotation speed of 950&#xa0;rpm and a tool travel speed of 28&#xa0;mm/min. Then the FSP-processed specimens were cut to standard dimensions for tensile and hardness testing using a wire cut electrical discharge machine (WEDM). To characterize the microstructure of the processed region, scanning electron microscopy (SEM) was used. Based on the microstructural examination of the Weld Nugget Zone (WNZ), severe dynamic recrystallisation and plastic deformation were observed in the WNZ due to tool rotation. The coarse grained structure that was formed in the fusion zone during PTIG welding was completely converted into fine grains that were uniformly distributed and equiaxed, due to the stir effect of the tool pin during FSP. As a result, microstructural homogeneity was improved. Mechanical testing carried out on the welds showed that Ultimate Tensile Strength increased from 179&#xa0;MPa to 193&#xa0;MPa, an increase of 8%. In addition, the hardness in the WNZ increased from 56 HV to 84 HV, due to grain refinement and the more uniform distribution of precipitates that contribute to strength. Thus, FSP serves as an effective post-weld treatment for improving both the microstructural quality and the mechanical properties of these dissimilar alloys.</p>