The importance of vitamin D in health and disease is being increasingly recognized nowadays and lots of research is being carried out in this area. Thus, it is essential to understand about this vitamin and this narrative review is one such initiative. The main aim of this review is to provide a comprehensive and in-depth knowledge of the role of vitamin D in health and disease. A comprehensive literature search was carried out in the search portals of PubMed, Google Scholar and Indmed to identify the role of vitamin D in health and disease. Vitamin D is a fat soluble prohormone, synthesized in our epidermal cells following exposure to sunlight. The synthesized precursors of vitamin D are metabolically activated by 25-hydroxylation in the liver and 1-α hydroxylation in the kidney. The biologically active form of vitamin D is 1, 25-dihydroxycholecalciferol which binds to the vitamin D receptor to mediate its effects. Vitamin D plays a key role in maintaining calcium and phosphate homeostasis in the body. However, vitamin D is also found to have various pleiotropic effects like anti-inflammatory, anti-apoptotic, antifibrotic and immunomodulatory effects. The serum 25-hydroxyvitamin D levels are considered as indicator of body’s vitamin D stores. Deficiency of vitamin D is highly prevalent and is associated with various diseases like osteoporosis, hip fractures, myocardial infarction and malignancies of colon, breast and prostate.