This book presents diverse applications of fungi in medical, pharmaceutical, and environmental sciences. It discusses the intricate processes involved in fungal metabolite production, bioactive compound discovery, and genetic engineering, highlighting their critical roles in addressing global challenges, such as chronic diseases, drug development, and environmental sustainability. This book examines the growing importance of fungi in the biopharmaceutical industry, including their use in immunotherapy, vaccine development, and precision medicine, while also exploring the novel applications of fungal nanobiotechnology in drug delivery systems. The chapters explore challenges in antifungal drug development and food safety, particularly regarding mycotoxins, and offer practical insights into diagnostic techniques for fungal infections. This book also addresses the global regulatory standards for fungal products and the ethical considerations surrounding the advancement of fungal biotechnology.