Mushrooms have long been valued not only for their culinary appeal but also as a rich source of bioactive compounds with notable health-enhancing properties. Among the diverse array of phytochemicals found in mushroom, polysaccharides, polyphenols, and terpenoids emerge as the most biologically significant constituents. This chapter provides a comprehensive examination of the structural diversity biosynthetic pathways and biological functions of the principal classes of compounds. Particular emphasis is placed on polysaccharides, especially β-glucans, due to their well-documented immunomodulatory, antineoplastic, and prebiotic activities. Recognized for their potent antioxidant and anti-inflammatory properties, these compounds play a crucial role in mitigating disease associated with oxidative stress. Additionally, this diverse group of secondary metabolites exhibits a broad spectrum of pharmacological properties, including antimicrobial, anticancer, and neuroprotective effects. Furthermore, these properties exhibit synergistic interactions among the compounds, with prospective applications in the development of functional foods, nutraceuticals, and therapeutic agents by integrating recent advances in mushroom biochemistry and biotechnology. This chapter highlights the critical role of these natural compounds in promoting human health and underscores their potential in the realm of integrative medicine.