Multiple myeloma (MM) remains an incurable hematologic malignancy, despite the development of numerous innovative therapies during the past two decades. Immunotherapies are changing the treatment paradigm of MM and have improved the overall response and survival of patients with relapsed/refractory (RR) MM. B cell maturation antigen (BCMA), selectively expressed in normal and malignant plasma cells, has been targeted by several immunotherapeutic modalities. Chimeric antigen receptor (CAR) T cells, the breakthrough in cancer immunotherapy, have revolutionized the treatment of B cell malignancies and remarkably improved the prognosis of RRMM. BCMA-targeting CAR T cell therapy is the most developed CAR T cell therapy for MM, and the US Food and Drug Administration has already approved idecabtagene vicleucel (Ide-cel) and ciltacabtagene autoleucel (Cilta-cel) for MM. However, the development of novel BCMA-targeting CAR T cell therapies remains in progress. This review focuses on BCMA-targeting CAR T cell therapy, covering all stages of investigational progress, including the innovative preclinical studies, the initial phase I clinical trials, and the more developed phase II clinical trials. It also discusses possible measures to improve the efficacy and safety of this therapy.