A total of 600 one-day-old male Ross 308 broiler chickens with an average body weight of 43.00 ± 0.42 g were used in a 35 d growth assay to investigate the supplemental effects of three levels (600, 1200, and 1800 β-glucanase units kg^-1) of β-glucanase on growth performance, nutrient digestibility, blood parameters, and meat quality in wheat–barley–soybean-meal-based broiler diet. During days 19–35 and overall period, chickens’ body weight gain and feed conversion ratio were significantly (P < 0.05) improved linearly following the levels of β-glucanase supplementation. The digestibility of crude protein and gross energy were significantly (P < 0.05) increased linearly with the levels of β-glucanase supplementation. Significant linear increase (P < 0.05) due to increasing β-glucanase supplementation was observed for blood urea nitrogen (BUN) concentration. Increasing β-glucanase supplementation did not influence (P > 0.05) the meat quality. In conclusion, broiler diets supplementation with increasing β-glucanase could improve the growth performance, enhance the digestibility, and modulate the concentrations of BUN linearly. Meat quality was not influenced.