Grain refining and microstructure homogenization are fundamental challenges for enhancing the performance of the materials. One of the effective ways to solve these challenges is the Friction stir processing (FSP) technique. This paper investigates the FSP parameters’ impact on the microstructure, hardness, wear, and corrosion behavior of A356 Al–Si cast alloy. The FSP parameters are rotational speed (355–900 rpm), trasverse speed (10–40 mm min-1), and two different tool geometries. The results revealed that the intense plastic deformation and dynamic recrystallization fragmented the needle-shaped eutectic silicon particles. The particle size change was more pronounced as the rotational speed was increased than the transverse speed and the pin profile tool geometry. The fragmented and homogeneously distributed Si particles in the investigated alloy increased their hardness, wear, and corrosion resistance compared with those of the unprocessed base metal. The hardness increased by two times, and the wear rate reduced by ten times, while the corrosion rate decreased by 200 times than the BM at lower tool rotational speeds and higher transverse speed. The Possible reasons were discussed for these enhancements.