Here, the effect of microwave-dried black soldier fly (Hermetia illucens) larvae meal (HILM) as a dietary protein source on the growth performance and health of broilers was evaluated. A total of 126 male broilers were randomly allocated to three treatments (six replicates of seven birds per group): control diet (CON) of corn and soybean meal and two experimental diets in which soybean meal was replaced with 25% (25HILM) or 50% (50HILM) HILM. The broilers were slaughtered at 35 d to determine the apparent ileal digestibility (AID), volatile fatty acid (VFA) profiles, and length and weight of the small intestine. Blood samples were collected from 36 randomly selected birds (12 broilers per treatment) to determine serum parameters and haematological traits. Average daily gain, feed intake, and AID of protein were decreased (P<0.05) in the 50HILM group compared with those in the CON group. Dietary HILM increased (P<0.05) the relative length of the entire digestive tract and total VFAs in the caecal digesta. Serum low-density lipoprotein cholesterol was the lowest (P<0.01), but the triglyceride levels were the highest (P<0.05) in the 50HILM group. The serum phosphorus level was lower in both HILM diet-fed groups (P<0.01), whereas the creatine phosphokinase level was lower in the 50HILM group than in the CON group. In contrast, the 50HILM group showed higher (P<0.05) monocyte and red blood cell distribution width-standard deviation. In conclusion, dietary microwave-dried HILM positively influenced the VFA and cholesterol levels; however, growth performance was negatively affected by malnutrition caused by low protein digestibility in the 50HILM group. Microwave-dried HILM is a valuable ingredient for broiler diets, with up to 25% substitution showing no detrimental effects on growth performance and health. Further studies are needed to improve HILM digestibility.