The present study was conducted to investigate the effects of dietary fiber source levels on the fecal ammonia nitrogen, growth performance, carcass traits, gastrointestinal tract development, and intestinal morphology of broilers. A total of 420 one-day-old unsexed broiler chicks were individually weighed and randomly divided into 5 groups, each with seven replicates of twelve chicks. Rice hulls (RH) and soybean hulls (SH) were ground through a hammer mill with a 2-mm screen. The RH and SH experimental diets were as follows: 0% (control); 2.5% RH; 2.5% SH; 5% RH; and 5% SH. No significant differences were found in growth performance and fecal ammonia nitrogen among the dietary treatment groups (p>0.05). Compared with the control, the experimental diets with 2.5% SH significantly decreased the wing weight of chickens (p<0.05), while no significant differences in the weight of the other visceral organs were observed. Compared with the control, broilers in the 5% SH group had a longer jejunum and ileum (p<0.05). Feeding the broilers SH and RH had no effect on the villus area and crypt depth of the intestine. Compared with the control, the experimental diet with 2.5% RH significantly increased the duodenal villus height of chickens (p<0.05). These findings suggest that the inclusion of 5% SH in the diets resulted in improved intestinal morphology without negatively affecting growth performance and carcass traits.