This work was intended to inspect the impacts of addition of different dietary selenium sources (Sodium selenite, selenium-enriched yeast, and seleno-methionine) on the growth parameters and carcass characteristics of Muscovy ducks. Also, hematological, serum biochemical parameters, immune status, antioxidant enzymes, gene expression, and economic efficiency were investigated. Forty-eight Muscovy ducklings (two weeks old) were randomly divided into four equal groups (12 ducklings/each). The 1^st group (negative control) was given the basic diet without selenium addition, while sodium selenite was added to the diet in the 2^nd group. The 3^rd and 4^th groups were induced by the basic diet with selenium-enriched yeast and seleno-methionine, respectively (0.4 mg selenium /kg diet). Results showed that ducks fed the basal diet, along with various forms of selenium, exhibited improved body weight gain and performance index. The 3^rd and 4^th groups displayed the highest values of the carcass traits, the relative weights of some internal organs, and muscle selenium content compared with the 2^nd group (sodium selenite) and the negative control group. All selenium groups showed reduced levels of cholesterol, triglycerides, low density lipoprotein, and malondialdehyde (MDA) values, and there was a significant improvement in high density lipoprotein, red blood cell count, hemoglobin levels, white blood cell count, lymphocytes, neutrophils, immunoglobulin levels (IgA, IgM, IgG), and activity of superoxide dismutase (SOD) and glutathione peroxidase (GPX); also, both growth (insulin-like growth factor) and immune (interleukin-10) related genes were up-regulated. Conclusively, supplementation of organic selenium led to appreciable enhancements in all assessed parameters used in this study.