Research on the CBP gene family in plants is scarce, with only sporadic reports on its association with immune responses. No systematic study has explored how CBP family genes regulate pepper resistance against Phytophthora capsici. Here, we focused on pepper CaCBP2, an RNA-binding protein, whose expression was significantly induced by P. capsici. Functional validation via VIGS and heterologous overexpression confirmed CaCBP2 as a negative regulator of pepper resistance to P. capsici. Based on physiological assays, transcriptome sequencing and WGCNA, we speculate it may mediate immune responses by regulating antioxidant systems, defense hormone metabolism, and disease resistance-related genes. Our findings fill the relevant research gap, enrich the role of RNA-binding proteins in plant anti-phytophthora defense, and provide a novel target for crop disease-resistant breeding.