Milk and derived products contain essential nutrients, such as proteins, lactose, minerals, vitamins, and enzymes. Additionally, despite of their low concentrations in milk, many other minor constituents present important physiological and/or technological roles (e.g. hormones, growth factors). Dairy industries face many challenges regarding milk processing. Also, the full knowledge on these constituents' physiological roles and effects on health is still lacking. Technological advances, innovative research approaches using metabolic engineering, systems and synthetic biology, and novel production methods will allow the production of higher amounts of such constituents, to produce them in such a way that recovery is easier and to produce differentiated compounds, thus revolutionizing the fields of personalized nutrition and functional foods. This chapter focuses on the description of the minor milk constituents, their applications and main technological challenges. Future perspectives and concerns related to these constituents are discussed.