In this study, effects of dietary supplementation of dried tomato powder (DTP) and red pepper powder (DPP) on the antioxidant mechanisms, immune system, cytokines, egg production performance, and egg quality were investigated in a total of 90, 30-week-old hens. The study groups were fed on a diet containing 4% DTP and 4% DPP, respectively for 30 days, while the control group received a commercial laying hen feed. Egg production and egg quality parameters, differential leukocyte count, heterophil functions, serum cytokine, malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), ascorbic acid, and glutathione peroxidase (GSH-Px) levels were measured. It was determined that serum tumor necrosis factor-alpha (TNF-alpha) levels increased (P = 0.018) and heterophil (P = 0.033) and monocyte (P = 0.020) percentages decreased in the DPP group compared to both control and DTP groups. In the same hens, serum transforming growth factor-beta (TGF-beta) level (P = 0.029) and oxidative burst (P = 0.021) increased compared to the control group, but interleukin-4 (IL-4) (P = 0.014) level and SOD activity (P = 0.021) increased compared to the DTP group. Phagocytic activity was higher in the DTP group compared to other groups (P = 0.003). In addition, it was observed that serum catalase level (P = 0.008), and egg yolk colour (P = 0.001) increased in both experimental groups compared to the control group. It was concluded that DPP and DTP used in this study strengthen the antioxidant defence system, increase heterophil functions, and positively affect cytokine production and egg colour, so it can be used as a safe feed additive in chickens.