The latest trends focus on increasing the nutritional value of food products, including yogurts, by fortifying them with bioactive compounds derived from natural ingredients, in line with the concept of “food-to-food fortification”. Mushrooms are a rich source of protein, dietary fibre, certain vitamins, minerals, and numerous bioactive compounds, including polysaccharides (β-glucans) and phenolic compounds. Biologically active substances found in mushrooms exhibit numerous biological properties, including antioxidant, anti-inflammatory, anti-carcinogenic, hypocholesterolaemic and immunomodulatory properties. This study aimed to determine the potential of edible mushrooms as functional additives in yogurt production, based on a review of the scientific literature. The study discusses the effects of various forms of mushroom additives (powders, aqueous and ethanolic extracts, polysaccharides, β-glucans) on the course of lactic acid fermentation, the growth and survival of lactic acid bacteria, and the physicochemical and sensory properties of yogurts. In most cases, the addition of mushrooms increased the activity of lactic acid bacteria, increased the acidity, viscosity, and hardness of yogurt, and reduced syneresis, thereby improving its stability. This effect is mainly due to mushroom polysaccharides, including β-glucans. In turn, the presence of antimicrobial and antioxidant compounds significantly limits the growth of undesirable microorganisms and slows lipid oxidation, thereby extending the shelf life of yogurts. The addition of edible mushrooms to yogurts, in various forms, is a safe and effective way to create a functional product that meets consumer expectations, but it requires optimising the form and concentration of the additive.