We report the reactivity of acetylenyl-terminated self-assembled monolayers (SAMs) on gold toward "click" chemistry, Huisgen 1,3-dipolar addition, leading to the formation of triazoles. After the formation of acetylenyl-terminated SAMs, the triazole formation was performed on the SAMs and the reaction was confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ellipsometry, and contact angle goniometry. "Click" chemistry has offered a versatile strategy for the functionalization in solution chemistry with mild reaction conditions and a high compatibility in functional groups, and our result shows that the reaction could be applied to acetylenyl-terminated SAMs for the introduction of useful functional groups to the surfaces.