Flavonoids are important natural products synthesized as secondary metabolites in various plants. These are polyphenolic compounds present in various plant parts such as fruit, bark, root, stem, and flower. Isoflavones are natural products belonging to class of flavonoids which are also known as phytoestrogens. Isoflavones and isoflavone-rich food are reported for their beneficial effects in many conditions such as hormone-related cancers, cardiovascular diseases, osteoporosis, and adverse postmenopausal symptoms. Kudzu, lupine, broccoli, cauliflower, barley, fava beans, and soy contain the maximum amount of isoflavones. Noncommunicable diseases are the group of conditions that are not mainly caused by an acute infection, result in long-term health consequences, and often create a need for long-term treatment and care. Various cancers, cardiovascular diseases, diabetes, and chronic respiratory diseases are the major types of noncommunicable diseases. Neurodegenerative diseases such as Alzheimer’s disease, epilepsy, chronic kidney disease, liver diseases, and genetic diseases such as sickle cell anemia are also important noncommunicable diseases. Daidzein, genistein, formononetin, and puerarin are the most explored isoflavones for their effects in different types of noncommunicable diseases. They have shown beneficial effects in the treatment and prevention of these diseases by acting as antioxidant, anti-inflammatory, anticoagulant, antilipidemic, antihypertensive, and antifibrotic. The present chapter focuses on the effects of various isoflavones in selected noncommunicable diseases.