Abstract: Bruton's tyrosine kinase inhibitors (BTKi) are a class of drugs approved for treating patients with B cell-related hematologic malignancies. They function by blocking B cell signaling, thereby affecting the development and proliferation of B cell-related tumors. Research has revealed that Bruton's tyrosine kinase (BTK) is also expressed in other cells, including mast cells, dendritic cells, granulocytes, platelets, and macrophages. Furthermore, BTK's downstream signaling pathways, such as the activation of phospholipase C gamma 2 (PLCγ2), Fc receptor signaling path ways, and Toll-like receptor signaling pathways, are associated with various diseases. These mechanisms provide a theoretical foundation for using BTK in treating diseases other than B cell-related tumors. This article reviews the progress in the application of BTK for non-B-cell malignancies.