ABSTRACT Cellulose‐based organic afterglow materials have gained considerable interest due to their low toxicity, cost‐effectiveness, and environmental benefits compared to traditional phosphors, with promising applications in anti‐counterfeiting, bioimaging, and sensing. Although extensive research has been conducted on cellulose and organic afterglow materials, a comprehensive review systematically discussing the underlying mechanisms and applications of cellulose‐based organic afterglow systems remains scarce. This review provides an in‐depth analysis of the origin of long‐lived afterglow emission in cellulose‐based materials, highlighting the critical roles of intramolecular and intermolecular interactions, and proposes strategic design principles for optimizing performance. Additionally, the current state of applications is summarized, and future research directions are outlined to guide further advancements in this rapidly evolving field.