Galectin-3 is a multifunctional protein that plays a critical role in inflammation, apoptosis, and fibrosis. It is considered a biomarker and therapeutic target in cardiovascular and neurodegenerative diseases, as well as pulmonary, hepatic, and renal fibrosis. Additionally, it is associated with diabetes and its complications. This review examines the clinical significance, therapeutic potential, and measurement methods of Galectin-3. A literature search was conducted using PubMed, Scopus, and Web of Science databases, including human studies published between 2000 and 2024. Findings highlight the importance of Galectin-3 as a biomarker and therapeutic target in clinical practice.