This study investigates the effects of casticin on osteoclastogenesis, aiming to elucidate its underlying mechanisms for potential clinical applications. We assessed the cytotoxicity of casticin using a CCK assay in RAW 264.7cell (murine cell line, from ATCC), which differentiate into osteoclasts upon RANKL treatment. Various concentrations (0.125, 0.25, 0.50 μM) were tested to establish a dose-dependent response. The effects of casticin on osteoclast differentiation and actin filament organization were evaluated through TRAP and F-actin staining. Additionally, qPCR and Western blot analyses were performed to assess gene expression. Concentrations exceeding 1.00 μM caused significant cytotoxicity. Notably, casticin at 0.50 μM significantly inhibited osteoclast differentiation and function, reducing marker gene expression, including c-FOS, NFATc1, CtsK, and MMP-9. Furthermore, casticin decreased phosphorylation levels of NF-κB and IκBα and downregulated BCL-2 expression. Our findings highlight casticin's potent regulatory effects on osteoclasts via the NF-κB/BCL-2 signaling pathways, suggesting potential therapeutic applications in bone-related disorders.