Lactose intolerance is a digestive condition characterized by an inability to digest lactose. It is prevalent in Asian countries, particularly in East Asia, where around 70–100% of the population exhibits this condition. In this regard, lactose hydrolysis has been identified as a critical step in the manufacturing of lactose-free products. This can be accomplished through acid hydrolysis, enzymatic hydrolysis and membrane reactors. One of the widely employed techniques in the food and dairy sectors is enzymatic hydrolysis, particularly utilizing β-galactosidase, a glycoside hydrolase enzyme that exhibits both hydrolytic and transgalactosylation abilities. In recent years, dairy producers have advanced their techniques and technologies through the utilization of immobilized enzymes, genetic engineering, membrane reactors and fermentation processes to facilitate the lactose hydrolysis. This chapter provides an overview of the numerous methods employed in lactose hydrolysis and highlights their significance.