To explore the effects of the orally administered exopolysaccharides derived from Lactobacillus plantarum HS-07 (EPS-07) on the immunity, antioxidative activity, and resistance against Aeromonas hydrophila in Cyprinus carpio. In this experiment, the EPS-07 (250 μg/mL, 500 μg/mL and 1000 μg/mL) were co-cultured with the head kidney cells of C. carpio. The control group was fed sterile saline, and the treatment group was fed different concentrations of EPS-07 (250 μg/mL, 500 μg/mL, and 1000 μg/mL), once a day, for 7 consecutive days, then challenged with A. hydrophila for 24 h. In vitro tests showed that for EPS-07 co-cultured with the head kidney cells of C. carpio, the proliferation ability, phagocytic activity, NO content, and expression of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and anti-inflammatory cytokines (IL-10 and TGF-β) were significantly increased (P<0.05). In vivo results showed that before infection with A. hydrophila, the NO content and expression of pro-inflammatory cytokines and anti-inflammatory cytokines in EPS-07 serum treatment groups were significantly increased (P<0.05). The content of T-AOC and GSH and the activities of T-SOD, GSH-Px, and CAT in the hepatopancreas of the EPS-07 treatment group were also significantly higher than those of control group (P<0.05), and the content of MDA decreased in a concentration-dependent manner (P<0.05). After A. hydrophila infection, EPS-07 inhibited the release of NO, upregulated the expression of anti-inflammatory cytokines, and downregulated the expression of pro-inflammatory cytokines. In conclusion, EPS-2 has potent immunoregulatory effects at the cellular and host level, which can improve the immunomodulatory, antioxidant effects, and disease resistance against A. hydrophila in C. carpio.