TIM-3 (T cell immunoglobulin and mucin domain-containing protein 3), also known as HAVCR2, is a crucial immune checkpoint molecule that is extensively expressed on various immune cells, including Th1, Th17, Treg, dendritic cells, monocytes, macrophages, and NK cells. The role of TIM-3 in the tumor immune microenvironment is particularly significant, as it is highly expressed on tumor-infiltrating CD8+ T cells and regulatory T cells (Tregs), and is co-expressed with PD-1, participating in the regulation of tumor immune evasion and T cell exhaustion. TIM-3 exerts its immune suppressive function by binding to its ligands, which include galectin-9 (Gal-9), phosphatidylserine (PtdSer), carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM-1), and high mobility group box 1 (HMGB1). These interactions lead to Th1 cell apoptosis, T cell exhaustion, and immune suppression, thereby facilitating tumor cells to evade immune surveillance. In cancer treatment strategies, TIM-3 has emerged as a promising target. Furthermore, the expression level of TIM-3 correlates with poor prognosis in certain types of cancer, making it a potential prognostic biomarker.