Despite the increased use of aluminium alloys in several industries, their common concern is the difficulty of joining dissimilar alloys using welding techniques. Based on this, the primary purpose of this research is to assess the mechanical characteristics of dissimilar joining of heat-treatable 6061 and non-heat-treatable 5083 aluminium alloys by gas tungsten arc welding and to discover the link between microstructure and mechanical properties. Similar welds were also implemented and evaluated in order to more properly analyze and compare the outcomes. The quality of the weld generated after establishing the health of the joint using non-destructive testing was evaluated by destructive bending, tensile, metallographic, and hardness tests to check the mechanical and microstructural qualities. The intended dissimilar weld was produced under the parameters of pulse current 120-80 amps, voltage 20 volts, welding speed 15 cm/min, and filler 5356. It should be highlighted that the dissimilar weld had the maximum joint efficiency, and with perfect control of welding settings and the absence of flaws, only 36% loss of strength was recorded when compared to the base metal. Metallographic images revealed that the formation of hot cracks in the dendritic structure of the weld metal is the major cause of strength loss for 5083 similar weld and the production of numerous porosities in the weld metal for 6061 similar welds.