A total of 300-day-old cobb 500 broiler chicks were allotted in a completely randomized design to five dietary treatments each replicated thrice, with 20 chicks per replicate. Chestnut phytobiotic was included at 0g, 100g, 125g and 150g/100 Kg diet while Oxytetracycline was included at 111g/100kg diet. Data was collected on nutrient digestibility, villi morphometry and intestinal microbial activity. All data collected were subjected to analysis of variance and significant differences among treatment means were compared using the Duncan’s Multiple Range Test. Birds fed diets containing 100g phytobiotics was significantly (P< 0.05) higher in values for red blood cell, monocytes, eosinophils and basophils. There were significant (P< 0.05) differences for values of Lactobacillus spp and Bacillus spp, whereas non-significant (P> 0.05) differences were observed for Escherichia coli, Clostridium spp and Salmonella spp. Intestinal bacteria count revealed that Lactobacillus spp, a beneficial bacteria was significantly higher and best in diet containing 100g phytobiotics (15.33 x10 3 cfu/g) when compared to that of the control (5.00 x10 3 cfu/g) but similar to that fed oxytetracycline (10.67 x10 3 cfu/g). Supplementation with phytobiotics also increased the concentration of Bacillus spp. In conclusion, supplementation of chestnut phytobiotics at 100g/100Kg significantly improved Lactobacillus spp and Bacillus spp which are beneficial bacteria.