The controllable synthesis and design of group IB metal (i.e., Au/Ag/Cu) and their alloy nanoclusters (IB-NCs) rely on an elucidation of the conversion mechanism, bonding preference, and structure–property relationships. In the past decades, the development of cluster-to-cluster transformation and spectroscopic tracking strategy have provided important mechanistic insights that greatly help researchers improve synthetic skills and explore the application of IB-NCs. Specifically, with the aid of DFT calculations, the structural information of cluster-to-cluster conversion, including the intermediates and active sites, can be deduced from the atomic level. In this review, the conversion mechanisms of IB-NCs in the past three years have been reviewed to summarize the key factors influencing structural transformation and reactivity. The three types of cluster-to-cluster conversion (i.e., foreign metal source, foreign ligand, and other reagents/condition-induced conversion) were highlighted for further synthesis and design of functional nanoclusters.