In traditional oriental medicine, nutgalls of Rhus chinensis have been used to treat various gastrointestinal and respiratory disorders. This study aimed to investigate the benefits of nutgalls of R. chinensis on bone loss and obesity in ovariectomized mice fed with a high-fat diet. Following surgical menopause induction, nutgalls of R. chinensis was orally administered for 4 weeks. Body weight gain and organ weights were measured. Histopathological examinations and UHPLC-MS/MS analysis were performed. Nutgalls of R. chinensis remarkably decreased obesity, gonadal fat, and bone loss in ovariectomized mice fed with a high-fat diet. Nutgalls of R. chinensis inhibited adipocyte differentiation of multipotent bone marrow stromal cells and reduced fat accumulation in gonadal fat, liver, and bone tissues. In UHPLC-MS/MS analysis, 27 phytochemicals containing gallotannin derivatives and flavonoids were identified by comparison with mass fragmentation of authentic standards. Taken together, the results demonstrate the beneficial effects of nutgalls of R. chinensis and its phytochemicals to manage postmenopausal bone disorders and obesity.