Atomically precise gold nanoclusters protected by thiolate ligands, Aun(SR)m, have emerged as a new class of nanomaterial in recent years. Many different sizes of Aun(SR)m nanoclusters have been synthesized and some have been crystallographically characterized. These atomically precise Aun(SR)m nanoclusters exhibit strong electron-energy quantization effects due to their ultra-small size (1–2 nm diameter), in contrast with the continuous electronic conduction band in metallic gold nanoparticles. These unique nanoclusters have also been demonstrated to be promising catalysts for a wide range of reactions, such as selective oxidation and hydrogenation, and carbon–carbon coupling reactions. These atomically precise Aun(SR)m nanoclusters (especially Au25(SCH2CH2Ph)18) can serve as new model catalysts and provide an opportunity to correlate the catalytic properties with the intrinsic structure of gold nanoclusters, and such structure–property correlation offers exciting insights into the mechanistic aspects of gold nanocluster-catalyzed reaction processes.