In tropical and subtropical climates, the low tolerance of rabbits to high ambient temperatures is a major issue. The current study assessed the efficacy of using selenium (Se), inactivated yeast, and their combination as alternatives to antibiotic (colistin) for 8 weeks in growing rabbits reared during summer season. A total of 100 five weeks old New Zealand White male rabbits (average body weight 694 ± 7.33 g) were randomly allocated into five groups: (1) control (basal diet); (2) colistin (basal diet + 120 mg colistin/kg); (3) inactivated Saccharomyces cerevisiae yeast (basal diet + 1000 mg/kg); (4) Se (basal diet +0.3 mg/kg); (5) inactivated Saccharomyces cerevisiae yeast+Se (basal diet + 1000 mg inactivated yeast/kg + 0.3 mg Se/kg). All tested supplements were added to the diet on fresh basis. The results showed that Se, inactivated yeast, and their combination improved (P < 0.05) feed conversion ratio during the experimental period (1–8 weeks) compared to control group. In comparison to the control group, total blood cholesterol was reduced (P < 0.05) in the treated groups. Moreover, blood selenium levels were elevated in groups fed on diets supplemented with Se alone or in combination with inactivated yeast. Interestingly, dietary supplements decreased (P < 0.05) malondialdehyde (MDA) levels as well as enhanced (P < 0.05) catalase (CAT) and glutathione peroxidase (GPx) activities. Villus height was increased (P = 0.001) more in the treated groups than in the control group. In contrast, villus width, crypt depth, and submucosa thickness were significantly decreased in supplemented animals compared with those unsupplemented. In summary, the results indicate the possibility of using Se, inactivated yeast, or their combination as alternatives to antibiotic and to enhance feed efficiency, antioxidant capacity, and gut health in growing rabbits raised under hot climatic of summer condition.