Macrophages are a class of innate immune cells with strong plasticity. They can polarize into different phenotypes, serving with various functions, such as phagocytosis and chemotaxis, which is involved in the development of diseases. RNA-binding protein quaking (QKI) regulates monocyte differentiation, macrophage polarization and various cellular functions through RNA splicing, translocation and expression. QKI regulates the differentiation of monocytes into macrophages, and QKI deficiency promotes the polarization of macrophages into M1 type, which exerts a pro-inflammatory phenotype. In contrast, QKI overexpression promotes macrophage polarization into M2 type. Additionally, QKI affects macrophage phagocytic receptor and chemokine expression. Due to the variations in tissue-resident macrophages’ features, QKI modulates macrophages in the pathogenesis of diseases (atherosclerosis, inflammatory bowel disease, etc.) through diverse mechanisms, which mainly involves cyclicAMP response element binding protein (CREB) transcription factor regulation, signal transducer and activator of transcription 1/nuclear factor κB (STAT1/NF-κB) inflammatory signaling pathway and pre-mRNA splicing of phagocytic receptor.