The present study aimed to evaluate the impact of coenzyme Q10 (CoQ10) supplementation in high-energy (HE) or normal-energy (NE) diets for growing rabbits raised in summer conditions on their growth, carcass traits, thyroid hormone levels, and immune response. To achieve this, a 2 × 2 factorial design was employed, incorporating two energy levels in the diet (10.40 and 11.52 MJ kg⁻¹, donates as NE and HE, respectively) supplemented with either 0 or 30 mg of CoQ10 per kg of diet (donates as NQ10 and SQ10, respectively). The feeding trial was conducted using forty male rabbits (637.2±11.7g and aged 35 days) for eight weeks. The findings indicated that the inclusion of HE feed led to a significant improvement in feed conversion ratio, daily weight gain, relative growth rate, and final body weight. Furthermore, rabbits fed HE diets exhibited notable increases in total protein, lysozyme, and T4 concentrations in blood serum, alongside a decrease in ALT levels. The inclusion of CoQ10 significantly improved growth parameters, feed conversion, serum total protein, albumin, IgG, lysozyme, and T4 concentrations. Rabbits fed HE+ SQ₁₀ and HE+ NQ₁₀ diets showed significantly higher feed intake, final weight, relative growth rate, and daily weight gain compared with those fed NE+ NQ10 diet. Rabbits receiving HIM + SQ10 and HIM + NQ10 exhibited the best feed conversion rates and increased economic efficiency. In summary, growing rabbits raised in summer climates demonstrated a favorable response to CoQ10 supplementation and high-energy diets, showcasing enhanced economic efficiency, growth, and feed conversion ratio.