Abstract: Bruton’s tyrosine kinase (BTK), a cytoplasmic tyrosine kinase, plays a central role in the activation of B cells and granulocytes, operating downstream of B cell and Fcγ receptors, and is considered an attractive target for treating autoimmune diseases. Preclinical investigations have demonstrated that inhibition of BTK activity holds promise as a potential therapeutic strategy for inflammatory immune responses such as autoimmune diseases and allergies. This review provides an overview of the mechanisms by which BTK contributes to immune-related diseases and summarizes current research on the development of BTK inhibitors for treating these conditions, aiming to offer novel insights into non-oncology applications for BTK inhibitors.