Achyranthes japonica extract (AJE) is a multifuctional products that express anti-inflammatory, antioxidant and anti-microbial properties. This study was aimed to evaluate the effects of AJE addition to standard and low crude protein (LCP) diet on growth performance, nutrient digestibility, excreta bacterial count, excreta noxious gas emissions, breast meat quality, and organ weight of broiler chicken. A total of 340 one-day-old Ross 308 broilers [initial body weight (BW) of 43.10 ± 1.46 g, 5 replicate cages per treatment, and 17 birds per cage] were randomly distributed into 1 of 4 dietary treatment groups for a 35 day trial. The diets were provided based on three age stage of the broiler. In the starter stage broiler were fed basal diet. Experimental diet were fed to broiler from day 8 to 35. In growing (days 8-21) and finishing (days 22-35) stage broiler were fed: Standard crude protein (SCP) diet and LCP diet with 0.025% and 0.05% of AJE supplementation respectively. Here, the SCP and LCP diets were 21.50% and 20.86% CP during days 8-21 and 20.00% and 19.40% CP during days 22-35, respectively. The SCP diets with 0.025% AJE supplementation resulted in higher (p < 0.5) BW gain (BWG) at finishing stage and a tendency to lower feed conversion ratio and BWG in the overall period compared to LCP diets with or without AJE supplemenation. Moreover, dry matter and nitrogen digestibility were increased with SCP diet along with 0.025% of AJE. No significant difference was found in meat quality parameters except for pH. Interestingly, the NH3 gas emission to the environment was found to be less with different levels of CP and AJE supplementation. Therefore, we concluded that the addition of 0.025% AJE to the SCP diet improved broiler growth performance and nutrient digestibility with low fecal NH3 emissions.