The production of bioethanol as a clean liquid fuel in a cost-effective way is highly desired by global energetics. Sugar beet molasses is a renewable and cheap substrate for the production of biotechnological products. Therefore, the aim of the current study was the optimization of an industrial medium from molasses for bioethanol production using the Taguchi statistical experimental-design method. First, the growth rate of yeast cells and the amount of ethanol produced by the Saccharomyces cerevisiae strain sahand 101 were investigated in aerobic and aerobic–anaerobic conditions. The yeast strain produced 8% (v/v) bioethanol in a medium containing molasses with 18% Brix in aerobic–anaerobic conditions. The main factors of the medium, including molasses, ammonium sulfate, urea, and pH, were optimized for the increase of bioethanol production by the Taguchi method. Bioethanol production reached 10% (v/v) after optimization of the medium in flask culture. The yeast strain produced 11% (v/v) bioethanol in the bioreactor culture containing the optimized medium, which is an acceptable amount of bioethanol produced from molasses at the industrial scale. The results showed that the Taguchi method is an effective method for the design of experiments aiming to optimize the medium for bioethanol production by reducing the number of experiments and time.