β-glucan is a naturally occurring non-starch polysaccharide formed by β-glycoside linkages between D-glucose monomers. Beta-glucan is found in significant quantities in various sources such as grains, fruits, fungi, algae, yeast, and bacteria. The recent emergence of beta-glucan has garnered considerable interest due to its beneficial impact on human health. This article provides a systematic overview of the sources, structure, technological functions, and practical applications of β-glucan in fermented dairy products. Gel formation, high moisture-binding capacity, enhanced yield of completed goods, texture formation, and original sensory indicators are just some of its pronounced technological roles in the composition of dairy products. The utilization of β-glucan derived from yeast and mushrooms has been found to be advantageous in providing biologically active compounds that contribute to the functional properties of the final product.