Black soldier fly (Hermetia illucens) is one of the most intensively studied insect species for use in animal nutrition. Despite the recognized nutritional potential of BSF larvae fat, there remains a lack of comprehensive scientific data regarding its effects on blood chemistry, immune function, nutrient digestibility, and the palatability of food in dogs. In this study, we aimed to evaluate the effects of replacing poultry fat with black soldier fly (BSF) larvae fat on faecal parameters, blood biochemistry, immune responses of dogs and their nutrient digestibility, food preference, and the lipid oxidation of foods. Three experimental diets were formulated: a control diet (containing 6% poultry fat), BSF3 (3% poultry fat +3% BSF larvae fat), and BSF6 (6% BSF larvae fat). BSF6 exhibited the lowest dry matter and organic matter digestibility. Although faecal pH and consistency scores were not significantly influenced by the dietary fat source, the total fatty acid concentrations in the faeces decreased with the substitution of BSF larvae fat with poultry fat. Also, BSF larvae fat reduced the protein and ether extraction digestibility and palatability of the diets. However, it had no adverse effects on the health status of the dogs.