Single-atom catalysts (SACs) have attracted extensive attention owing to their outstanding catalytic performance and nearly complete atom utilization efficiency. However, the environmental sustainability of SACs across their full life cycle has not yet been systematically investigated. This review emphasizes the necessity of integrating life cycle assessment (LCA) into SACs to support their sustainable development. By analyzing the structural characteristics, synthesis strategies, and representative application fields, this study examines how LCA principles can be employed to reveal the hidden environmental burdens associated with raw material extraction, synthesis processes, usage stages, and end-of-life management. Based on existing LCA case studies of catalytic materials, this review identifies the key challenges in the SACs field and proposes a preliminary framework for sustainable SAC design with LCA as a guiding approach. Finally, the review summarizes the current challenges and future perspectives, emphasizing that developing more specific evaluation standards, improving database construction, and adopting dynamic assessment methods are essential to shift LCA from a passive evaluation tool to an active design strategy that drives the green development of next-generation SACs.