Abstarct: Water deficit poses a significant obstacle to the growth of agricultural plants worldwide, impeding the cultivation of most crops. Water deficit and drought stress hinder plants from achieving their maximum genetic yield, resulting in reduced agricultural productivity. This growth-limiting factor directly impacts over 20% of crop yields each year. In recent decades, the utilization of certain growth stimulants has emerged as a captivating area of research. These stimulants offer the advantage of being easy to use, readily available, and less time-consuming compared to traditional plant breeding methods. Among these stimulants, yeast extract and 24-brassinosteroids have proven to be particularly noteworthy, as they play a crucial role in enhancing plant resistance to both biotic and abiotic stresses. To investigate their efficacy, a research study was conducted over two crop years (1399 and 1400) at the research farm of the Faculty of Agriculture at Shahrood University of Technology. The study employed a factorial split plot experiment design, baxsed on a randomized complete block, with four replications, focusing on the effects of these growth stimulants on cowpea plants. The experimental treatments include water deficit stress in the form of increasing the frequency of irrigation as the main factor in three levels (every 8 days (no stress), every 12 days (mild stress) and every 16 days (severe stress)) and spraying the extract yeast at two levels (12 g/L) and 24-brasinosteroid at three levels (5 and 10 μM) were as sub-factors. The outcomes of this research revealed that water deficit stress had a significant impact on various aspects of the cowpea plants. It led to a noticeable decrease in morphological traits, yield components, photosynthetic pigment content, and ultimately, the yield. By simultaneously and individually applying various levels of 24-brassinosteroid and yeast extract, a substantial enhancement was observed in the morphological traits, yield components, photosynthetic pigment content, and yield of cowpea plants. The combined use of these growth stimulants played a crucial role in mitigating the detrimental effects of dehydration stress. They achieved this by bolstering the defense mechanisms of the cowpea plants, primarily through augmenting the levels of enzymatic and non-enzymatic antioxidants. Consequently, these growth stimulants positively influenced the cowpea plants' ability to cope with the stress and improve their yield. By increasing the content of enzymatic (catalase, ascorbate peroxidase, guaiacol peroxidase, polyphenol oxidase and superoxide dismutase) and non-enzymatic (phenol, proline and flavonoid) antioxidants, degradation of photosynthetic pigments and content of malondialdehyde decreased in cowpea plants under water stress. The results of this research showed that the treatment of cowpea plants with 10 μM 24-brasinosteroid under mild and severe water deficit conditions leads to a 25% and 20% increase in the weight of 20 pods, respectively, compared to the absence of 24-brasinosteroid. Also, the application of 10 μM 24-brasinosteroid along with yeast extract increased the seed yield and the number of pods per plant by 14 and 15%, respectively, compared to the absence of 24-brasinosteroid and yeast extract. The findings of this research confirmed that the treatment of cowpea plants with yeast extract under mild and severe water deficit conditions leads to an increase of 6 and 11% in the weight of 20 pods, respectively, compared to the normal conditions. Overall, the findings of this study highlight the considerable potential of utilizing 24-brassinosteroid and yeast extract as functional stimulants to enhance the tolerance of cowpea plants under water-stress conditions. These results hold particular relevance for regions facing water scarcity, where the cultivation of cowpea can benefit from the application of these growth stimulants.