The research examines how varying shot peening parameters affect the surface properties of AA5083 aluminum alloy, specifically looking at topography, mechanical traits, and surface morphology. Shot peening treatment is conducted using a custom system with stainless steel shots ranging from 4–8 mm diameter, peening durations of 30–60 min, and shaft speeds of 500–1000 rpm. Surface characteristics are assessed through hardness depth-wise measurement, surface roughness, and tensile properties. The study investigates phase transformation and grain refinements using X-Ray Diffraction (XRD), Electron Backscatter Diffraction (EBSD), and Transmission Electron Microscope (TEM). Full-depth profile and lattice strain study with localized plastic strain are analyzed using XRD, with EBSD estimating the depth of plastically strained regions. A multi-criteria decision-making approach is used to identify the optimal peening parameters based on hardness, tensile strength, and surface roughness, employing analysis of variance (ANOVA) and Grey Regression analysis.