Current work explores the effect of gray relational analysis (GRA) in finding optimized parameter setting in order to investigate the quality of friction stir-welded aluminum 6061 alloys. Nine experimental runs based on the Taguchi technique were discovered maximizing tensile and flexural strength. The current study considers three factors: tool rotating speed, welding speed, and tool offset. Tensile and flexural strength were measured to assess the quality of the welded structure. The optimized operating conditions of weld determined by Taguchi for tensile strength are 1000 rpm, 20 mm/min, and 1 mm, whereas 1400 rpm, 15 mm/min, and − 1 mm were estimated to be optimal parameters for flexural strength. Furthermore, GRA technique has been employed to maximize both performances simultaneously. The optimum conditions obtained for GRA involving responses of 1400 rpm, feed of 25 mm/sec, and tool offset of -1 mm. This research infers that speed and feed are the most influential factors to maximize both responses.