The experiment was conducted to assess the physico-mechanical properties of Ossimi ewe wool when supplemented with selenium (Se) during the wool growth phase. Forty indigenous dry Ossimi ewes, weighing 45–50 kg and aged three to four years, were randomly allocated into four groups with similar average body weights. The first, second, and third treated groups received supplementation of 20, 30, and 40 mg of inorganic selenium (Se) per kg of dry matter per head per day, while the control group was only given the basic diet. The results demonstrated significant enhancements in certain physical attributes, including increased staple length (STL) and fiber diameter (FD), decreased contaminants, and higher clean wool weight. Staple strength and elongation percentage increased in all treated groups. Furthermore, all treated groups exhibited a notable rise in blood plasma selenium levels. In summary, selenium supplementation enhanced certain wool characteristics in Egyptian sheep.