While obesity is a well-known health threatening condition worldwide, effective pharmacological interventions for obesity suppression have been limited due to adverse effects. Therefore, it is important to explore alternative medical treatments for combating obesity. Inhibition of the adipogenesis process and lipid accumulation are critical targets for controlling and treating obesity. Gardenia jasminoides Ellis is a traditional herbal remedy for various ailments. A natural product from its fruit, genipin, has major pharmacological properties; it is anti-inflammatory and antidiabetic. We investigated the effects of a genipin analogue, G300, on adipogenic differentiation in human bone marrow mesenchymal stem cells (hBM-MSCs). G300 suppressed the expression of adipogenic marker genes and adipokines secreted by adipocytes at concentrations of 10 and 20 μM, which effectively reduced the adipogenic differentiation of hBM-MSCs and lipid accumulation in adipocytes. It also improved adipocyte function by lowering inflammatory cytokine secretion and increasing glucose uptake. For the first time, we show that G300 has the potential to be a novel therapeutic agent for the treatment of obesity and its related disorders.