Cowpea (Vigna unguiculata (L) Walps) is a major legume in many underdeveloped nations farmed mostly for its grains in Nigeria and West Africa. However, a variety of storage pests infest the grain, with Callosobruchus maculatus being a major field pest that causes farmers to suffer unimaginable misery and significant losses. To evaluate the effectiveness of Aloe barbadensis leaf powder as a preventive measure against C. maculatus infesting stored cowpea, laboratory studies were carried out in the Department of Parasitology and Entomology at a temperature of 28 °C and 80% relative humidity. The toxicity was carried out at five dosage rates (0.25 g/mL, 0.5 g/mL, 1.0 g/mL, 1.5 g/mL, and 2.0 g/mL) of the test plant powder and (0.12 g/mL) standard alpha-cypermethrin and a (0.0g/mL) untreated control per 50g of cowpea grains. Ten adults of one-two days old C. maculatus was introduced into each vial, and the experiment was set up in a completely randomized design of five treatments replicated three times. The responses of C. maculatus to the insecticides and damage assessments were based on percentage adult mortality, oviposition, F₁ emergence, percentage seed damage, and percentage weight loss. The result showed that the plant contains alkaloids, flavonoids, tannins, cardiac glycosides, saponins, and cyanogenic glycosides in different levels of concentrations. Of the six phytochemicals evaluated, Tannins had the highest concentration followed by flavonoid, saponin, cardiac glycoside, cyanogenic glycoside, and alkaloid. Also, tannins were present in the highest amount (92.62mg/100g) of the phytochemicals analyzed followed by flavonoid (29.26mg/100g), saponins (17.53mg/100g), cardiac glycosides (14.65mg/100g), alkaloid (4.72mg/100g), and cyanogenic glycoside (2.35mg/100g). The highest dosage of 2.0g/mL A. barbadensis powder extract caused a mortality of 93.3% while 0.25g/mL caused 40% mortality respectively. Also, mortality was time-dependent. The recorded death rate was 4% at 24 hours of exposure, and it rose to 75.7% over 168 hours. This was a substantial difference, nevertheless (P<0.05). The LD₅₀ and LD₉₀ of the leaf powder extracts were calculated as 0.34g/mL and 1.72g/mL, respectively, after the probit values were regressed and plotted against log dosage. A straight line and regression coefficient, R2= 0.9923, were also obtained from this process. Also, regression co-efficient for time, R²= 0.9149 was obtained from which LT₅₀ and LT₉₀ of the leaf’s extract was determined as (128.02 hours and 414.45 hours) respectively. Additionally, there was a significant difference (P < 0.05) in the mean oviposition on seeds treated with the various doses of the test plants compared to the untreated control. For the plant leaf extracts, the mean F₁ progeny that emerged on seeds treated with 2.0g/ml was lower (18.3) than the control (72.0). The treatment dosages of 2.0g/ml (18.3) and 0.25g/ml (30.6) differed significantly (P < 0.05). There are significant differences (P < 0.05) in the mean percentages of damaged seeds between the treatments. The highest dosage of the test plant had the lowest mean percentage seed damage (12.5%) compared to the control (80.2%) and was significantly different (P < 0.05) between them. The powder dosages had a notable impact on the reduction of cowpea seed weight loss. Weight loss was lowest at 2.0g/ml (21.2%) and highest at 1.5g/ml (24%), with a significant difference (P<0.05) between the two dosages of the test plant. According to the studies, Aloe barbadensis was successful in lowering cowpea pest attacks.