The present work evaluated the immune-enhancing and growth-promoting effects of dietary peptidoglycan on black tiger shrimp (Penaeus monodon). Peptidoglycan was supplemented at levels of: 0.00, 0.10, 0.20, 0.40 g peptidoglycan kg-1 diet. The first feeding trial was conducted for 30 days to evaluate peptidoglycan supplementation on P. monodon immunological responses and disease resistance. Results showed that groups with 0.20 g peptidoglycan kg-1 diet exhibited highest survival in white spot syndrome virus challenge test which is linked to higher immunological responses. Another 60-day feeding trial was conducted to evaluate peptidoglycan influence on shrimp growth, nutrient retention, diet digestibility, digestive enzyme activities, and cellular energy allocation. Results indicate that supplementation of 0.20 g peptidoglycan kg-1 diet enhanced shrimp growth attributed to better feed conversion efficiency and lipid retention resulting from improved apparent dry matter digestibility of the diet, digestive enzyme activities, and cellular energy allocation. Collectively, the present data suggest the immunoprotective effects against WSSV infection and the elucidation of growth-promoting effects of 0.20 g peptidoglycan kg-1 diet in juvenile P. monodon.