Abstract: Natural killer T (NKT) cells constitute a distinct subpopulation of T cells that express T-cell receptors and NKT cell markers. NKT cells are one of the bridges that link the innate and adaptive immune systems and play a vital role in regulating immune responses in tumors, autoimmune diseases, and microbial infection. Multiple myeloma is a hematologic malignancy due to the uncontrolled proliferation of plasma cells. Multiple myeloma cells express CD1d and are sensitive to lysis by CD1d-restricted natural killer T cells. In recent years, the antitumor effects of NKT cells in multiple myeloma have become a hot research topic. Here, we reviewed the biological characteristics of NKT cells and their applications in multiple myeloma.