This research sought to elucidate the mitigating role of dietary grape seed extract (GSE) anti-HS agent alterations in blood parameters, immune function, oxidative balance, and inflammatory responses in growing rabbits. A 120 growing rabbits, (age 5 weeks, 657.32± 6.12 g) were randomly assigned to 4 treated groups (30 rabbits in each group). For 8 weeks, under natural thermal stress environments, these groups were fed diets supplemented with varying levels of GSE: 0 (basal diet as a control group), 100 (GSE100), 200 (GSE200), and 400 mg/kg diet (GSE400).Stressed rabbits fed diets added with GSE displayed significantly (P<0.001) higher growth indices and feed conversion ratio (FCR) as compared to rabbits fed basal diets. Feeding stressed rabbits diets fortified with GSE resulted in notably decreased levels of serum biochemistry [Alanine (ALT) and Aspartate (AST) transaminases, Gamma-glutamyl transferase (GGT), lactate dehydrogenase (LDH), creatinine, and uric acid] and lipid profile, while significantly improved levels of blood proteins (P<0.001). Total antioxidant capacity (TAC) in rabbits fed diets with 200 or 400 mg of GSE was notably greater (P<0.01) than in the other groups. All GSE-supplemented diets significantly improved superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities compared to control diets (P<0.01). MDA and myeloperoxidase were significantly (P<0.01) reduced by dietary GSE in a dose-dependent manner. HS substantially diminished serum levels of IgG and IgM in rabbits, and dietary GSE supplementation effectively mitigated this reduction (P < 0.01). Dietary GSE inclusion significantly (P<0.01) reduced interleukin-4 (IL-4) levels in a dose-dependent manner. Compared to GSE0, GSE fortification increased (P<0.01) interleukin-10 (IL-10) levels and nitric oxide in rabbits. Taken together, the evidence suggests that GSE serves as a valuable feed supplement for stressed rabbits, promoting both health and growth. Conclusively, these findings indicate that GSE is a promising feed supplement for boosting growth, blood biochemistry, and overall productivity in environmental stress rabbits. Future investigations should delve deeper into the underlying mechanisms by which GSE mitigates the adverse effects of heat stress in animal systems.