<p>Black garlic is a processed product prepared by ageing raw garlic bulbs under high–temperature and high-humidity conditions for several days or weeks. Black garlic has a better sensory appeal, with a sweet–sour taste, a characteristic sulfur-sweet-roasted aroma, and a soft, elastic, jelly like texture. In the last decade, black garlic has acquired a reputation in the functional food market due to its antioxidative, anticancer, anti-inflammatory, cardioprotective, hepatoprotective, and anti-diabetic activities. This review provides an insight into processing techniques, including pretreatments for the production of black garlic, phytochemical changes during the ageing, and their effect on the quality parameters of black garlic, Maillard reaction products, changes in the aroma profile of black garlic, and physiological role of constituents of black garlic in various diseases. This review will be helpful in expanding the industrial applications of black garlic as a functional food.</p>