AbstractImmunotherapy is used to regulate systemic hyperactivation or hypoactivation to treat various diseases. Biomaterial‐based immunotherapy systems can improve therapeutic effects through targeted drug delivery, immunoengineering, etc. However, the immunomodulatory effects of biomaterials themselves cannot be neglected. In this review, we outline biomaterials with immunomodulatory functions discovered in recent years and their applications in disease treatment. These biomaterials can treat inflammation, tumors, or autoimmune diseases by regulating immune cell function, exerting enzyme‐like activity, neutralizing cytokines, etc. The prospects and challenges of biomaterial‐based modulation of immunotherapy are also discussed.