In this study, we investigated the effects of dietary supplementation (n = 40 pigs/treatment) with bamboo powder (0, 1, 2 and 3%) for 38 days. We evaluated growth performance, blood metabolites, and carcass characteristics of fattening pigs and gas emission and microbial populations in pig manure, to obtain data on pork producers for environmental management. We obtained the following results. First, supplementation with increasing amounts of bamboo powder had a significant (P < 0.05) effect on feed intake, feed efficiency, and glucose contents (except for initial and final body weight, weight gain, carcass characteristics, and blood urea nitrogen). In terms of blood metabolites, glucose and blood urea nitrogen tended to decrease with increasing amounts of bamboo powder. Second, the amounts of ammonia, methane, amine, hydrogen sulfide, and acetic acid were reduced by increasing amounts of bamboo powder when compared with the controls (P < 0.05). However, there were no significant differences in pH, propionic acid, iso-butyric acid, butyric acid, iso-valeric acid, and valeric acid among all treatments. The lowest gas emission was observed when 3% bamboo powder was used. Third, supplementation with increasing amounts of bamboo powder tended (P < 0.05) to increase the total number of bacteria, Lactobacillus spp., and yeast, but E. coli, Salmonella spp., and Shigella spp. were not detected in any treatment. In conclusion, the results of this study suggest that supplementation with bamboo powder was effective in reducing gas emission and inhibiting pathogen populations in pig manure by lowering the pH of the manure.