AA8011 aluminium alloy is widely used in automotive radiator applications due to its good corrosion resistance, adequate strength, and excellent thermal conductivity. However, its mechanical performance after welding is strongly influenced by the thermal cycle and the heat input during TIG welding. This study investigates the effect of welding current variations (115 A, 120 A, and 125 A) on the post-weld mechanical properties and microstructural evolution of AA8011 alloy. Tensile testing, Vickers microhardness mapping, macro-microstructural observations, and weld-bead geometry evaluation were performed in accordance with ASTM and AWS standards. Results show that welding current significantly affects grain morphology, hardness distribution, and tensile performance. The optimum mechanical response was obtained at 120 A. The novelty of this work lies in providing a comprehensive mechanical–microstructural characterisation of TIG-welded AA8011 alloy, thereby contributing scientific insights toward the optimisation of welding parameters for lightweight radiator components.