This study explores the optimization of wire arc additive manufacturing (WAAM) parameters for SS316L stainless steel using response surface methodology (RSM) and validates the results through COMSOL finite element analysis (FEA). SS316L, known for its excellent corrosion resistance and mechanical properties, was selected for its relevance in critical industries such as aerospace and biomedical engineering. The research addresses the challenge of optimizing process parameters voltage, current, and travel speed to improve bead geometry and mechanical performance. RSM accurately predicted bead width, height, and penetration depth, leading to significant improvements. The optimized parameters yielded tensile strengths of up to 580 MPa, compressive strengths over 600 MPa, and microhardness values as high as 210 Hv. Microstructural analysis revealed a uniform austenitic phase distribution with reduced porosity, ensuring material integrity and enhancing mechanical properties. Physical tests confirmed a high density of 7.96 g/cm3 with minimal porosity. FEA simulations closely matched experimental outcomes, with deviations of less than 5%, validating the numerical models. Fractography analysis demonstrated ductile fracture mechanisms, reinforcing the reliability and toughness of the WAAM-fabricated SS316L parts. These findings underscore the potential of WAAM for producing high-performance components, with applications in the aerospace, automotive, and biomedical industries.