Abstract: Obesity is a global health issue which affects individuals’ day-to-day activities, working life and appearance, and poses significant risks to health. High incidence of obesity also imposes social and economic burdens on countries. Potential safety risks associated with weight-loss drugs have attracted increasing attention in recent years. New naturally-sourced products with safe and effective weight-loss properties have gradually become a focus of research. Triterpenoid saponins are bioactive substances with many physiological functions. This review summarizes and discusses the inhibitory effects and potential mechanisms of various triterpenoid saponins on obesity and reviews the recent progress of research into triterpenoid inhibition of digestive enzyme activity, regulation of appetite, energy consumption in lipid metabolism, and intestinal microflora. Potential applications of triterpenoid saponins in nutritional and healthcare products are explored.