The human body is colonized by diverse microorganisms, with bacteria being the most extensively studied. However, fungi, collectively known as "the mycobiota," are increasingly recognized as integral components of the microbiota, inhabiting nearly all mucosal surfaces. Commensal fungi influence host immunity similarly to bacteria and contribute to other essential functions, including metabolism. This emerging understanding positions fungi as potential biomarkers for the diagnosis and prognosis of various diseases. In this review, we explore the dual roles of fungi as both commensals and pathogens, and the potential of antifungal antibodies to serve as diagnostic and prognostic tools, especially in chronic immune-inflammatory non-communicable diseases, including inflammatory bowel disease, rheumatoid arthritis, multiple sclerosis, and neurodegenerative disorders. Finally, we address current challenges and outline future perspectives for leveraging fungal biomarkers in clinical practice.