The review discussed the brewing industry’s by-products’ biotechnology potential. If these byproducts are not properly managed, they may result in residues that are a significant waste and contamination of the environment. Beer production always results in the creation of different wastes and byproducts. The major prevalent by-products are surplus yeast, spent grain, and spent hops. These are produced from the primary raw materials required to make beer, which are barley malts, hops, and yeasts, respectively. Although these three main brewery by-products are readily accessible all year round, dairy farmers mostly purchase them to use as animal fodder for calves or as a simple place to dump waste. However, because of their diverse composition—which includes minerals, nitrogen, and carbon—they represent a significant potential resource for utilisation in biotechnological processes. Many efforts have been made to use them in biotechnological processes, such as being used as a substrate for microbial cultivation, in fermentative processes to produce some value-added compound (xylitol, arabitosl, ethanols, and lactic acids, etc.), or just as a raw material for extracting other compounds like sugars, proteins, acids, antioxidants, and other bioactive substances. Eliminating industrial byproducts is a solution to pollution issues from an environmental perspective, and as such, it deserves significant consideration. This article reviews the primary attributes and possible uses of some of the brewery by-products, with a particular emphasis on their application in processes of biotechnology.