Interferon regulatory factor 4 (IRF4) is one of the transcription factors in the interferon regulatory factor family. In the normal physiological process, IRF4 protein is a key factor regulating B cell development, such as early B cell development, pre-B cell switch recombination, mature B cell somatic hypermutation, and also a key factor regulating plasma cell differentiation. In addition, in recent years, it has been reported that Irf4 gene abnormalities or abnormal protein expression is closely involved in the occurrence and development of a variety of B cell or plasma cell tumors. This article reviews the physiological role of IRF4 in the differentiation and maturation of B cell or plasma cells, how IRF4 participates in the occurrence and development of B cell or plasma cell tumors, and its potential therapeutic target for B cell or plasma cell tumors.