This study evaluated the role of Moringa oleifera leaves extract (MOLEx) in improving the performance and health of rabbits during the fattening period. The growth, carcass measurements, serum immunity, lipid profile, liver and kidney functions, digestive enzymes, antioxidant condition, and cereal microbiota of rabbits have been examined. A total of 100 New Zealand White male rabbits (5-week-old) were randomly distributed into five groups and were fed on the basal diet only or the basal diet supplemented with graded levels of MOLEx (1, 2, 3 or 4 g/kg diet) for 8 weeks. Animals in each group were divided into 10 replicates, with two animals each. Results showed that dietary supplementation of MOLEx at levels of 1, 3 and 4 g/kg feed improved growth performance (P<0.05) including LBW (7, 9, 11, 13 weeks), BWG (5–13 weeks) and FCR (11–13 and 5–13 weeks). The inclusion of MOLEx in rabbits’ feed (3 and 4 g/kg) increased carcass %, dressing % and spleen % and decreased duodenum pH and cecal pH. Abdominal fat % was significantly lowered after the treatment with MOLEx. Lipid profile, liver and kidney functions, and cecal microbiota (increasing beneficial bacteria and reducing harmful bacteria) of growing rabbits were positively affected by MOLEx levels. The dietary supplementation of MOLEx improved most of antioxidant biomarkers of growing rabbits. The dietary supplementation of MOLEx (2, 3 and 4 g/kg) increased immunological indicators (IgM, IgG, IgA, lysozyme and complement 3), and lowered cortisol level compared with the control group. Digestive enzymes (protease, lipase and amylase) activities of rabbits were positively affected by MOLEx levels (3 and 4 g/kg feed). In conclusion, the inclusion of MOLEx in rabbits feed can be effective in improving productive performance, kidney and liver functions, digestive enzymes, antioxidant biomarkers, immunological indicators, cecal microbiota and carcass traits.