Periodontitis is a chronic inflammatory disease triggered by plaque biofilm and impacts patients' quality of life and overall health. In recent years, fibrin (ogen), serving as a crucial molecular bridge connecting inflammation and coagulation, has been drawing increasing attention for its role in periodontitis. This review explores the association between fibrin (ogen) and periodontitis and its underlying mechanisms, with a focus on how it regulates neutrophil and macrophage functions, interacts with periodontal pathogens, and activates signaling pathways such as nuclear factor κB, thereby synergistically driving periodontal inflammation and bone resorption. The aim is to provide a theoretical basis for intervention strategies targeting fibrin (ogen) in the management of periodontitis.