Both selenium (Se) and the probiotic Bacillus regulate animal metabolism to help in defense and improve performance. The aim of this study was to evaluate the effect of supplemental selenium nanoparticles (SeNPs) and Bacillus subtilis (BS) in the form of SeNPs-enriched Bacillus subtilis (SNEBS) on growth performance, nutrient digestion, nitrogen balance and serum biochemistry in growing rabbits. One hundred and five 42-day-old New Zealand White male growing rabbits weighing 762 ± 13.8 g were randomly distributed in five equal groups (21 each), each treatment having seven replicates (3 rabbits each). Dietary treatments were control (no probiotic), while the other four groups were supplemented with probiotics (BS alone at doses 0.5 × 10⁹ and 1 × 10⁹ cfu /kg diet, SNEBS at doses 0.5 × 10⁹ and 1 × 10⁹ cfu /kg diet), respectively. The feed duration was 70 days. The results showed that rabbits fed a diet supplemented with either BS or SNEBS had higher final body weight (FBW) and average daily gain (ADG), digestibility coefficients of DM, CP, NDF, and ADF, nitrogen balance, and nitrogen absorbed (p<0.05) than rabbits fed a control diet. Adding different levels of BS and SNEBS to rabbit diet resulted in a considerable rise in the dressing percentage weight of the rabbits. Total protein, albumin, and globulin were significantly increased (P < 0.05), but serum cholesterol, triglycerides, HDL, and LDL were significantly decreased (P < 0.05) by supplementation with different levels of BS and SNEBS. It may be concluded that at the studied doses, the probiotic Bacillus subtilis alone or SeNPs-enriched Bacillus subtilis can be applied in rabbit rations to boost productivity with no adverse effects.