Dendropanax morbifera ( D. morbifera ), known as Dendro, means ‘omnipotent drug’ (Panax), and has been called the panacea tree. Various studies on D. morbifera are currently ongoing, aiming to determine its medicinal uses. The present study investigated the anti-inflammatory effects and underlying mechanism of a natural extract of D. morbifera leaves (DPL) in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. In the present study, the following assays and models were used: MTT assay, nitric oxide (NO) assay, western blotting, ELISA and mouse models of atopic dermatitis. DPL extract markedly reduced the production of NO, inducible NO synthase and interleukin-6, as well as the nuclear translocation of nuclear factor-κB (NF-κB). Additionally, the LPS-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2), P38 and c-Jun N-terminal kinase (JNK) was suppressed by DPL extract. Taken together, these results indicate that NF-κB, ERK1/2, P38 and JNK may be potential molecular targets of DPL extract in the LPS-induced inflammatory response. Subsequently, the present study investigated the effects of DPL extract in a 2,4-dinitrochlorobenzene-induced atopic dermatitis mouse model. Ear thickness, serum immunoglobulin E levels and histological analysis revealed that the DPL extract was effective in attenuating the inflammatory response. These results indicate that DPL extract has anti-inflammatory potential and may be developed as a botanical drug to treat atopic dermatitis.