Due to an aging population and the prevalence of illnesses associated with modern lifestyles, mushrooms, well known for their nutritional value and health-promoting properties, are becoming an increasingly important part of the diet. They are consumed in various forms, including food, nutraceuticals, and dietary supplements. A relatively new trend involves incorporating mushrooms or their components as additives and supplements to enhance the quality and functionality of traditional food products. The processing and preservation methods of fresh mushrooms can significantly impact the activity of resulting powders, extracts, or other functional forms used in food additives, supplements, and fortified foods. The functional benefits of mushrooms are frequently attributed to their antioxidant and anti-inflammatory properties. However, to date, the literature lacks comprehensive reviews that consolidate existing knowledge on mushroom-based food additives and products enriched with them. Therefore, this review aims to compile and methodically analyze the existing data in this field, identify existing knowledge gaps, and outline future perspectives for the development and application of such products. Special attention is given to food supplementation with microencapsulated additives, which represent a promising form of functional powders. All these aspects are evaluated in terms of their antioxidant and anti-inflammatory properties. Finally, future perspectives on improving the health benefits of food through mushroom-based additives are discussed.