The scarcity of water resources in arid and semi-arid regions necessitates the search for drought-resistant varieties, as well as using of some treatments that reduce the impact of water stress. The present work was conducted in Upper Egypt at Sohag Governorate to study the response of four sugar beet varieties, i.e., Poseidon, Nancy, Gazelle and Lilly, to some bio-fertilizers under normal and drought stress. The field experimental was carried out in a Randomized Complete Blocks Design (RCBD) using a split-split plot arrangement with three replications. The biofertilizers treatments were; control, Vinasses at 5%, yeast at 5% and Vinasses + yeast at 5%. Supplying sugar beet varieties with the optimal irrigation compared with deficit irrigation (drought stress) significantly affected the quality indicators. The results illustrated the marked superiority of Poseidon beet variety over the other ones in all quality parameters determined. The results indicated that the addition of the bio-fertilizer yeast or Vinasses or both gave the lowest values for K, Na, (α-n), SL and SLY in both seasons. Bio-fertilizer, i.e., yeast and Vinasses mitigated the drought stress on sugar beet varieties. The application of Vinasses and yeast to Poseidon sugar beet variety under water stress gave the best results for quality traits of sugar beet. The application of yeast and Vinasses is an effective tool in reducing the negative effects of water stress on the quality of sugar beet varieties.