Triggering receptor expressed on myeloid cells 2 (TREM2) is a transmembrane receptor belonging to the immunoglobulin superfamily. It is primarily expressed on myeloid cells and microglia. Upon binding to its ligand, TREM2 activates downstream signaling pathways through the intracellular adaptor protein DAP12/DAP10, playing an important role in immune signaling. TREM2 is involved in the regulation of various biological processes, including phagocytosis, inflammatory reactions, and metabolic processes. Its significant role has been observed in the onset and development of various diseases. Recent research has highlighted the key role of TREM2 in the development of malignant tumors. Apart from regulating the biological behavior of tumor cells, TREM2 can also modulate the activity and function of immune cells within the tumor microenvironment, contributing to the formation of a suppressive immune microenvironment. This article aims to summarize the regulatory role of TREM2 in different types of malignant tumors and provide prospects for future research related to targeted therapies involving TREM2, thereby offering novel insights for research in the field of cancer prevention and treatment.