The current study was conducted for evaluation the effect of different sources levels of potassium fertilizer on the performance of cotton plants under the drought stress. Particularly cotton water applied efficiency, chemical and pigments content, vegetative growth, and yield characteristics were evaluated and compared among different sources levels of potassium-treated and non-treated drought-stressed plants to test the potential of this fertilizer as a tool for alleviating drought stress. A field experiment was conducted for the Sids Agricultural Research Station, Agricultural Research Center, Beni-Suef, Egypt 2020/2021. The results indicated that irrigation every 12 days gave highest values of leaf chemical and pigments content, vegetative growth and yield parameters, except earliness percentage and water applied efficiency which adversely affected and lint percentage, which unaffected. Foliar sprayed of potassium were significantly enhanced all studied abovementioned parameters, except earliness percentage, which negatively affected and lint percentage which did not respond to potassium application. The results of the interaction between irrigation and potassium treatments revealed that productivity of cotton plants grown under drought stress when fertilized with recommended rate (114 kg K2O ha-1) of potassium sulphate, 0.5% monopotassium phosphate or 0.5% dipotassium phosphate gave cotton growth and yield statistically equal to those grown under full-watered treatment. Therefore, it could be recommended to sprayed cotton plants grown under deficit water conditions with 0.5% monopotassium phosphate or 0.5% dipotassium phosphate or added 114 kg K2O ha-1 potassium sulphate.