<p>Wire arc additive manufacturing (WAAM) is an efficient method for producing large-scale structural components of titanium alloy; however, research on the corrosion behavior of these components remains limited. This study investigated the passivation behavior of Ti-6Al-4V alloy prepared under different conditions, including direct current (DC) arc with trailing shielding gas, as well as pulsed current arc with and without trailing shielding gas. The characterization was performed using electrochemical tests and XPS analysis. The results revealed that the DC WAAM sample exhibited the lowest corrosion current density, whereas the pulsed WAAM sample without trailing gas showed the highest in electrochemical tests. The preparation process did not alter the semiconductor nature of the passive films, and all three samples exhibited n-type semiconductor characteristics. The pulsed WAAM sample without trailing gas consistently showed higher passive film defect concentrations. The passive films formed on titanium alloys prepared with trailing shielding gas demonstrated superior compactness. This report provides new insights into the nature and behavior of the passive film formed on titanium-based alloys fabricated by WAAM, which is expected to benefit further understanding and potential engineering design for applications where corrosion resistance is critical.</p>