This study evaluated the effects of Mannan-oligosaccharides and βglucan (MOS-βG) and Saccharomyces cerevisiae yeast, individually or combined, on the physiological and immunological responses of growing New Zealand White (NZW) rabbits under different stocking densities. A total of 108 six-week-old male rabbits (weighing 938.42±18.15 g) were randomly assigned to eight experimental groups arranged in a 2 × 4 factorial design: two stocking densities—normal (NSD; 3 rabbits/cage, 12 rabbits/m²) and high (HSD; 6 rabbits/cage, 24 rabbits/m²)—and four dietary treatments (control, MOS and β-glucan at 1 ml/L water, S. cerevisiae at 1 g/L water, or their combination). Each treatment was replicated three times. Hematological parameters, serum cortisol levels, and immune responses were evaluated. MOS-βG supplementation significantly improved leukocyte counts, hematocrit values, and differential WBC profiles (P < 0.05), particularly under HSD. The combined treatment reduced cortisol to levels nearer control (3.98–6.6). Under HSD, the combined treatment attenuated the density-induced increase in splenic IL-1β expression, maintaining levels comparable to those observed under normal stocking density. Overall, dietary supplementation with MOS and β-glucan and/or S. cerevisiae mitigated the adverse effects of high stocking density and enhanced immune competence, supporting their use as effective nutritional strategies in intensive rabbit production systems.