<p>The alloy AZ61 has received little research attention when it comes to Al/Mg dissimilar friction stir welding (FSW) for lightweight structural applications, despite having remarkable mechanical and electrochemical properties. This study investigates the weldability, interface evolution, and corrosion characteristics of AA6061/AZ61 in butt joint configuration by designing experiments using response surface methodology. Analysis of variance on mathematical model of the response surface validated its adeptness. Transitions in tool–metal contact conditions were observed with the changing of parameters. Development of interpenetrating features significantly enhanced mechanical interlocking. Constitutive relations have been used to explain the relationship of Al₁₂Mg₁₇ layer thickness and AZ61 grain refinement in stir zone (SZ) with physical parameters. The microhardness gradually decreased from the AA6061 base metal toward the center of the SZ, due to the dissolution of strengthening precipitates. In contrast, when measured from the AZ61 base metal toward the SZ, the hardness increased because of grain refinement. The maximum value of ultimate tensile strength (UTS) obtained is 179&#xa0;MPa and is limited by Al₁₂Mg₁₇ with accompanied brittle fracture. Corrosion rate was recorded as 6.33&#xa0;mm/year for AA6061/AZ61 which is lower than that of previously reported studies. The results of this study highlight the potential of AZ61 as a high-performance alloy for Al/Mg FSW, offering enhanced mechanical strength and corrosion resistance.</p>