This study evaluated the use of cornelian cherry ( Cornus mas L.) fruit extract on the growth performance, immune responses, and disease resistance in common carp ( Cyprinus carpio ). A total of 192 fish (initial body weight of 18.34 ± 1.8 g) were randomly distributed in 12 tanks with 16 fish per tank (4 treatments with 3 replications) and fed with diets containing cornelian cherry extract (CCE 1 ) at the rate of 0, 0.25, 0.5 and 1%. The final weight of common carp fed CCE at 0.5% was significantly higher than fish fed 0 and 0.25% doses ( p < 0.05). In addition, weight gain and specific growth rate were increased, and feed conversion ratio decreased in fish-fed diets containing 0.5 and 1% CCE compared to other groups. The challenge test with A. hydrophila revealed that common carp-fed CCE had a lower mortality rate than the control. The lysozyme activity was markedly higher in common carp fed 0.5% of cornelian cherry extract than in control. The total immunoglobulin and total protein showed higher values in fish fed 0.5 and 1% than the control. The catalase gene showed higher mRNA levels in fish fed 0.5 and 1% than the control. Glutathione reductase gene expression was markedly upregulated in common carp fed 1% of CCE than the control and 0.25% groups. The glutathione S-transferase gene showed higher mRNA levels in fish fed 0.5 and 1% than the control and 0.25% groups. The superoxide dismutase gene expression was markedly higher in common carp fed 0.5% of CCE than in control. The CC-chemokine and interleukin-10 showed higher mRNA levels in fish fed 0.5% than the remaining groups. Hypoxia-inducible factor 1-alpha gene expression was markedly upregulated in common carp fed 1% of CCE than the control and 0.25% groups. The heat shock 70 kDa protein and interleukin-1 beta genes showed higher mRNA levels in fish fed 0.25, 0.5, and 1% than the control. In conclusion, the supplementation of CCE at 0.5–1% is recommended to enhance the growth performance and relieve the impacts of A. hydrophila infection in common carp.