The objective of this study was to evaluate the effect of the addition of fluted pumpkin leaves extract on the physicochemical properties, microbiological quality and organoleptic attributes of the soy milk using standard methods. Five blend ratios and codes of 100:0 (Sample A), 95:5 (Sample B), 90:10 (Sample C), 85:15 (Sample D) and 80:20 (Sample E) were developed for soy milk and fluted pumpkin leaves extract respectively. Results from this study revealed that increase in fluted pumpkin leaves extract supplementation in the soy milk increased the moisture (80.06 to 82.68%), fiber (0.58 to 0.76%), ash (0.71 to 0.96%), pH (5.99 to 6.50), while decreasing the protein (3.57 to 2.80%), fat (2.78 to 2.30%), carbohydrate (12.30 to 10.38%), titratable acidity (0.17 to 0.13%), total solids (19.27 to 18.60%), total bacteria (3.30×105 to 1.45×105 cfu/mL) and fungi (2.40×104 to 6.0×102 cfu/mL) loads. The fluted pumpkin leaves extract also appeared to have a bactericidal effect on the product as bacterial load decreased with increase in the concentration of the extract. The sensory evaluation revealed that Sample C containing 90% soy milk and 10% fluted pumpkin leaves extract was the most preferred blend among the samples containing the leaves extract. The formulated product could be useful to individuals who have lactose intolerance or heart-related diseases since it is practically free from lactose and cholesterol. It is recommended that flavour masking agents should be used to improve the herbal flavour of the product, to enhance its general acceptability and encourage consumption.