The present study aimed to evaluate the implication of silicon nutrition on activating physiological mechanisms for thermal adjustment and growth of cowpea plants under water restriction. Thus, two cowpea genotypes (Xiquexique and Novaera) were grown in plastic posts in a greenhouse and subjected to three levels of water stress (control, moderate and severe stress) and two silicon (Si) levels (0 - without and 2.0 mmol/L - with Si). In general, the growth data revealed that Xiquexique plants are more tolerant to drought than Novaera genotype. However, under moderate drought, Si-treated Novaera plants displayed elevated values of leaf area (LF), shoot dry mass (SDM), root dry mass (RDM) and total dry mass (TDM) as compared to those from treatments without Si. The superior performance of moderately drought-stressed Novaera plants under Si supplementation was attributed to restrict control of leaf temperature under water stress. Our findings evidence that silicon counteracts the drought harmful effects by promoting thermal adjustment and increasing water stress tolerance in cowpea plants.