Recent years have seen a growing convergence between digital, physical, and biological disciplines, heralding a major shift in agriculture and the food industry, led by advanced technologies, such as artificial intelligence, big data, smart sensors, robotics, three-dimensional printing, and blockchain, among others. These technological innovations constitute the core of the Fourth Industrial Revolution (called Industry 4.0) that is currently reshaping many agri-food sectors, including the dairy industry. Growing evidence shows that harnessing the power of Industry 4.0 technologies in the dairy sector could have several benefits, such as improved quality, traceability, and productivity, decreased production cost and time, and most importantly, from a sustainability point of view, reduced waste and by-products. This short review will focus on the potential of leveraging Industry 4.0 technologies in the reduction and valorization of waste and by-products in the dairy sector.