AbstractThe intrinsic deficiencies of nanoparticle‐initiated catalysis for biomedical applications promote the fast development of alternative versatile theranostic modalities. The catalytic performance and selectivity are the critical issues that are challenging to be augmented and optimized in biological conditions. Single‐atom catalysts (SACs) featuring atomically dispersed single metal atoms have emerged as one of the most explored catalysts in biomedicine recently due to their preeminent catalytic activity and superior selectivity distinct from their nanosized counterparts. Herein, an overview of the pivotal significance of SACs and some underlying critical issues that need to be addressed is provided, with a specific focus on their versatile biomedical applications. Their fabrication strategies, surface engineering, and structural characterizations are discussed briefly. In particular, the catalytic performance of SACs in triggering some representative catalytic reactions for providing the fundamentals of biomedical use is discussed. A sequence of representative paradigms is summarized on the successful construction of SACs for varied biomedical applications (e.g., cancer treatment, wound disinfection, biosensing, and oxidative‐stress cytoprotection) with an emphasis on uncovering the intrinsic catalytic mechanisms and understanding the underlying structure–performance relationships. Finally, opportunities and challenges faced in the future development of SACs‐triggered catalysis for biomedical use are discussed and outlooked.