<p>This study examines the synergistic effect of edge preparation geometry and material positioning configuration on the microstructural evolution and mechanical properties of dissimilar AA5083–AA8011 friction stir welded joints. Two edge conditions—plain and zigzag—were used, along with varying the positioning of AA5083 and AA8011 on the advancing and retreating sides, to fabricate butt joints. Significant grain refinement was seen in the stir zone by optical microscopy, with zigzag edge joints showing finer and more uniform grain structures than plain-edge joints. While plain joints displayed localized precipitate coarsening and compositional heterogeneity, zigzag joints demonstrated improved material mixing, uniform elemental distribution, and refined precipitation behavior, as confirmed by SEM and EDS analyses. In all joints, α-Al was found to be the dominant phase by XRD analysis. In zig-zag joints, a noticeable broadening of the peak and a decrease in the intensity of the intermetallic peak were observed, suggesting improved lattice strain and grain refinement. Stir-zone hardness for zigzag joints increased significantly, according to hardness measurements, with AA8011 positioned on the advancing side, yielding the highest average hardness. The configuration with AA8011 on the advancing side, which obtained the highest ultimate tensile and yield strengths, was found to have superior strength in tensile testing. Predominantly ductile fracture behavior was confirmed by SEM fracture analysis, and better tensile performance was correlated with fine, uniform dimples.</p>