Cerebral ischemia-reperfusion injury (CIRI) is a complex pathological process that arises when blood flow is restored to the brain after ischemia, often resulting in significant neuronal damage and triggering secondary inflammatory responses. This review explores the immune mechanisms underlying CIRI, focusing on the activation and polarization of resident central nervous system (CNS) cells-particularly microglia and astrocytes-and the infiltration of peripheral immune cells such as neutrophils, monocytes/macrophages, and T lymphocytes. We discuss the central role of microglia in the neuroinflammatory cascade, their polarization between pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes, and how this process influences neuronal damage and tissue repair. This review highlights the roles of the complement system, inflammasome activation, and blood-brain barrier disruption as key drivers of inflammation and neuronal injury. Additionally, we elaborate on the dynamic interactions between resident and infiltrating immune cells, which amplify inflammation and impede post-ischemic recovery. Finally, we discuss emerging therapeutic strategies targeting immune modulation, including cytokine regulation, microglial reprogramming, and targeted drug delivery systems, which offer promising avenues for improving outcomes in ischemic stroke.