Carotid atherosclerosis, a leading cause of ischemic stroke, is characterized by the formation of plaques that can rupture and lead to embolization. Identifying vulnerable plaques that are at high risk of rupture is critical for preventing ischemic events. Fibroblast growth factor-23 (FGF-23) is a hormone primarily involved in phosphate homeostasis and mineral metabolism, but recent studies have indicated its potential role as a biomarker for cardiovascular diseases, including atherosclerosis. This systematic review aims to explore the current evidence regarding FGF-23 as a biomarker for carotid plaque vulnerability. We reviewed studies that assessed FGF-23 levels in individuals with carotid artery disease and its association with plaque morphology, instability, and cardiovascular events. Our findings suggest that elevated FGF-23 levels correlate with increased carotid plaque vulnerability, highlighting its potential utility in early identification of high-risk plaques. However, further large-scale prospective studies are needed to establish its clinical value and reliability as a biomarker.