This study aims to optimize the Tungsten Inert Gas (TIG) welding parameters for joining AISI 316L stainless steel and Cu-ETP copper using 309L stainless steel filler rods. Welding dissimilar materials is challenging due to their significant differences in thermal and mechanical properties. The high thermal conductivity of Cu-ETP copper leads to rapid heat dissipation, causing uneven heat distribution at the weld interface. To address this issue, the research team applied a 1 mm offset of the welding torch toward the copper side to balance the heat input. They employed statistical analyses using ANOVA and the Taguchi method to determine the optimal process parameters. The results showed that the optimal welding current, welding speed, and gas flow for achieving high tensile strength (Rm) are 90 A, 0.5 mm/s, and 12 l/min, respectively. Among these, welding speed emerged as the most significant factor, influencing 48.74% of the weld characteristics. Mechanical testing confirmed that these parameters produced high-quality welds. Metallurgical analysis revealed minimal diffusion between the materials, preserving their distinct properties while minimizing the formation of undesirable intermetallic phases. These results highlight the effectiveness of TIG welding in creating robust joints between AISI 316L stainless steel and Cu-ETP copper for applications requiring a combination of both materials' properties.