<p>Metal nanoclusters have served as an emerging class of programmable nanomaterials with customized structures. However, it remains highly challenging to achieve the single-atom regulation of metal nanoclusters without altering their structural frameworks. Here, we achieve the single-point defects manipulation based upon a cluster pair of Au₂₁ and Au₂₂ by meticulously complementing the surface defects of the former nanocluster with an additional single-Au complex. The two nanoclusters exhibited identical geometric structures, but their pronounced quantum-confinement effects resulted in different electronic properties, evident in their distinct optical absorption and emission characteristics. Temperature-dependent steady-state photoluminescence spectra and femtosecond transient absorption spectra showed that the manipulation of a single-point defect in Au₂₂ inhibited non-radiative decay pathways, reduced electron loss at higher energy levels, and accelerated intersystem crossing, which ultimately enhanced its emission intensity. Overall, the Au₂₁ and Au₂₂ cluster system in this study provides a cluster platform with controllable surface single-point defects, enabling the regulation of the photophysical dynamics at the atomic level.</p>