Mushrooms are increasingly recognized not only as nutritious foods but also as sources of bioactive compounds with protective effects against diabetes, cardiovascular diseases, cancer, and neurodegenerative disorders. Their high fiber content, valuable micronutrients, and diverse bioactive molecules, combined with their culinary versatility, have fueled a global rise in consumption. This trend is further reinforced by the shift toward plant-based diets, where mushrooms contribute high-quality protein, umami flavor, and a fibrous texture, making them appealing alternatives to meat. Among edible mushrooms, Hericium erinaceus (Lion’s Mane) is distinguished by its unique morphology, delicate flavor, and remarkable medicinal potential. Rich in erinacines, hericenones, polysaccharides, and ergothioneine, it represents a promising candidate for both gastronomy and nutraceutical applications. This paper integrates a critical review of current knowledge with new experimental findings. Original data are presented on proximate composition, phenolic compounds, organic acids, amino acid profiles, and polysaccharides. In addition, a descriptive sensory lexicon was developed to address the lack of standardized evaluation for this species. By combining literature analysis with novel laboratory insights, this work underscores the potential of H. erinaceus as a functional food ingredient, particularly in the context of sustainable plant-based diets and health-promoting strategies. Future perspectives are outlined regarding clinical validation, technological innovation, and the broader role of mushrooms in advancing nutrition and food system sustainability.