Abstract: Macrophage migration inhibitory factor (MIF) is an enzyme-active pleiotropic cytokine that is expressed in various immune cells and tumor cells. MIF plays diverse roles in inflammation and tumor progression. It acts as a cytokine involved in immune response and inflammatory lesions. Additionally, MIF is closely associated with tumor proliferation, metastasis, and other tumor hallmarks, exerting a multifaceted influence on tumor occurrence and progression. MIF not only functions by being secreted into the extracellular space as a cytokine but can also be localized within the cytoplasm and nucleus, exhibiting diverse biological functions. As MIF in promoting tumor progression becomes increasingly recognized, MIF-based therapeutic strategies have become a hot research topic in oncology. Here, we provide a comprehensive review of MIF with different subcellular localization about their pro-tumoral functions. A better understanding of MIF in tumor biology will bring broader perspectives for the development of novel MIF targeting strategies and give promising direction for future tumor treatments.