Water scarcity in semi-arid regions stands out as the main environmental factor limiting cowpea (Vigna unguiculata (L.) Walp) yield. Therefore, foliar application of kaolin waste emerges as a strategy to mitigate water stress, ensuring the growth and production of agricultural crops. Therefore, this study aims to evaluate the effect of kaolin waste applied via foliar application as a water stress attenuator on the cowpea cultivar 'BRS Tapaihum'. The experiment was conducted in a greenhouse at the Federal University of Campina Grande (UFCG). Treatments consisted of four irrigation depths (50, 75, 100, and 125% of real evapotranspiration-ETr), without and with kaolin waste (50 g L-1), applied via foliar application, distributed in a completely randomized design, in a 4 x 2 factorial arrangement, with eight repetitions. Foliar spraying of kaolin waste associated with a level of 75% ETr promoted the highest value of plant height and, when associated with a level of 50% ETr, promoted the highest values of chlorophyll contents (a, b and total) and relative water content. Kaolin waste, when associated with the irrigation depth required by the crop (100% ETr), despite promoting the highest values of pod length and number of grains per pod, did not result in the highest total production per plant, obtained in the treatment with 100% ETr depth without foliar application of kaolin waste.