AbstractDiosgenin, an essential dietary steroidal sapogenin, possess multiple pharmacological activities. This study aimed to assess the effects of diosgenin on periodontitis and elucidate the mechanisms. Lipopolysaccharide (LPS)‐stimulated human periodontal ligament stem cells (hPDLCs) and a Porphyromonas gingivalis (P.g) plus ligation‐induced animal model were used for in vitro and in vivo studies, respectively. Inflammatory responses, nuclear factor κ‐B (NF‐κB) signaling and osteogenesis‐related markers were measured both in LPS‐stimulated hPDLSCs and in gingival tissue of periodontitis rats. Treatment with diosgenin significantly inhibited the production of tumor necrosis factor α (TNF‐α), interleukin (IL)‐1β, and interleukin (IL)‐6 and the activation of NF‐κB pathway in LPS‐stimulated hPDLSCs. Further, treatment with diosgenin enhanced the expression of osteoblast‐related genes and increased the osteogenic differentiation capacity. Further, activation NF‐κB pathway largely abolished the protective effects of diosgenin. Consistent with the in vitro studies, in vivo studies showed that administering diosgenin to periodontitis rats significantly lowered the levels of the TNF‐α, IL‐1β, and IL‐6 and the inflammatory transcription factor NF‐κB in gingival tissue. In addition, osteoblast‐related genes were promoted. Diosgenin attenuates periodontitis by adjusting NF‐κB signaling to inhibit inflammatory effects and promoting osteogenesis, suggesting diosgenin might be developed as a therapeutic strategy for treating periodontitis in the future.