Pigeonpea [Cajanus cajan (L.) Millsp.] is mostly grown in tropical and subtropical regions of the world. This member of the Fabaceae family is a protein-rich legume that, besides its regular use as a dal, has been used for a very long time in traditional medicine to cure a broad variety of diseases, including diabetes, food poisoning, constipation, pain, and inflammation. These therapeutic characteristics are associated with a wide variety of classes of secondary metabolites, the majority of which are categorized as phenolic compounds and include apigenin, cajanin, naringenin, quercetin, vitexin, and isovitexin. As a result of the various biological and pharmacological actions that have been recorded in published research over the course of the past several years, it is currently thought of as a possible herbal therapeutic intervention for a wide variety of ailments. This chapter presents an overview of the secondary metabolites of C. cajan, along with trends and technical breakthroughs in the work that is now being done on the biological and pharmacological activities of C. cajan for human food, health, and medicine.