Platycodon grandiflorus, in the family Platycodonaceae, has been traditionally utilized in China to treat sore throats, hoarseness, and coughs with phlegm. As a medicinal and food plant, P. grandiflorus has a long history of use. Recent research on natural medicine has highlighted the biological activity and potential medicinal benefit of P. grandiflorus, which has prompted in-depth studies. One of the main active compounds extracted from the root of this plant is platycodin D (PD). This compound has various beneficial properties, including anti-inflammatory, antitumor, antioxidant, metabolic regulatory, antiviral, hepatoprotective, and spermatogenic effects. Additionally, PD can serve as a vaccine adjuvant to increase the efficacy of vaccines. This article explores the potential mechanism of action in treating hepatocellular carcinoma, breast cancer, lung cancer, and diabetes. The pharmacokinetics and bioavailability of PD are also discussed. With advancements in basic research and clinical applications, PD is anticipated to become a significant therapeutic agent for treating inflammatory diseases, metabolic disorders, and cancer.