AbstractVarious nanomaterials as biocatalysts could be custom‐designed and modified to precisely match the specific microenvironment of diseases, showing a promise in achieving effective therapy outcomes. Compared to conventional biocatalysts, single metal atom catalysts (SMACs) with maximized atom utilization through well‐defined structures offer enhanced catalytic activity and selectivity. Currently, there is still a gap in a comprehensive overview of the connection between structures and biocatalytic mechanisms of SMACs. Therefore, it is crucial to deeply investigate the role of SMACs in biocatalysis from the atomic structure level and to elucidate their potential mechanisms in biocatalytic processes. In this minireview, we summarize catalysis regulation methods of SMACs at the atomic structure level, focusing on the optimization of catalytic active sites, coordination environment, and active site‐support interactions, and briefly discuss biocatalytic mechanisms for biomedical applications.