A six week feeding study was carried out to assess the effects of graded levels of indomie waste meal (IWM) as a substitute for maize in the diet of broiler chickens on growth performance, carcass traits, cost efficiency, digestive enzymes activities, and serum biochemical parameters. One hundred and twenty male one day-old Cobb 500 broiler chicks were used. The birds were weighted and assigned to equal six treatment groups as following: T1 (0% IWM), T2 (20% IWM), T3 (40% IWM), T4 (60% IWM), T5 (80% IWM), and T6 (100% IWM) in a completely randomized design. Each treatment had five replicates and each replicate contains four chicks. The Results of growth performance showed that the body weight gain was significantly highest (P < 0.05) in birds fed 60% IWM (2663 g / bird). The feed intake decreased gradually as IWM increased in the diet. Feed conversion ratio was significantly lowest (P < 0.05) in birds fed 60% IWM (1.65). It was revealed that the relative weight of gizzard, liver, intestine, and abdominal fat were significantly (P < 0.05) affected by the dietary inclusion of IWM. The highest recorded value of abdominal fat percent was (3.36) in group fed 100% IWM. The lowest recorded value of liver % was (1.91) in group fed 60% IWM. Cost and return analysis revealed that the feed cost decreased because IWM increased in the diet. Total return and net profit were significantly highest in birds fed 60% IWM. Also there was an improvement in the pancreatic digestive enzymes activities with dietary inclusion of IWM. There were significant increase in amylase and lipase activities while significant decrease in protease activity. There was a significant increase in the total cholesterol as dietary IWM increased. Based on the study's findings, indomie waste meal was recommended to substitute maize up to 60% level in the broiler chickens diet.