This literature review is devoted to the tuberous yacon (Smallanthus sonchifolius), a perennial plant of the family Asteraceae, which is widely used in traditional medicine. Yacon tubers are characterized by a sufficiently high content of inulin for industrial production. The data provided in the review show that Smallanthus sonchifolius has a proven prebiotic effect due to its high content of fructooligosaccharides as well as other chemical compounds and has great potential as a prebiotic. In addition to the prebiotic effect, yacon has a wide range of pharmacological effects, including antidiabetic, hypoglycemic, hypolipidemic, anti-inflammatory, antitumor, immunostimulatory, antioxidant, antidepressant, hepatoprotective, spermatogenic, antibacterial, antifungal, antiparasitic, analgesic. Infusions made from yacon leaves can be not only effective agents against hyperglycemia, but also a relatively rich source of polyphenolic antioxidants. Yacon has potential as a plant supplement to treat male infertility and normalize low testosterone levels, such as in LOH-syndrome. The diversity of pharmacological action of yacon is due to the content of different groups of biologically active substances described in the review. The underground organs, leaves, and flowers of yacon contain various chemical compounds, including phenolic acids, sesquiterpene lactones, fructooligosaccharides of inulin type β (2→1), tannins, flavonoids, saponins, and anthracene derivatives.