Low-temperature Au–Au bonding was achieved under vacuum ultraviolet irradiation in the presence of oxygen gas (VUV/O₃). The Au surfaces obtained after the VUV/O₃ treatment were analyzed by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) measurements. The results indicate that the amount of carbon-based contaminants was dramatically decreased and that there was no serious damage to Au surfaces caused by the VUV/O₃ treatment. The Au–Au bonding temperature was successfully reduced to 150°C after the VUV/O₃ treatment. The average shear strength was approximately 56 MPa, and cross-sectional scanning electron microscopy (SEM) images of the bonded samples confirmed the absence of voids and cracks. Therefore, VUV/O₃ treatment is highly effective for achieving low-temperature Au–Au bonding.