In this study, a relatively new manufacturing process - friction stir welding (FSW) was used to join 3 mm thick AZ91D plates. The process was conducted at a traverse speed of 50 mm/min and rotational speed of 1000 rpm; and the weld sample’s microstructural and mechanical properties were evaluated. The microstructural analysis was conducted with an optical microscope. The mechanical properties evaluation includes tensile and microhardness tests. The microstructural analysis shows a defect-free sound joint of the materials with absence of voids and wormholes. The tensile strength of the weld was enhanced significantly and a joint efficiency of 109% was achieved. However, there was no substantial effect on the ductility and hardness properties of the weld sample. In conclusion, the FSW process is an efficient and sustainable technique to join and enhance the tensile properties of similar AZ91D alloys.