Ivermectin is a widely used broad-spectrum antiparasitic agent employed in both companion animals and livestock. While generally safe for mammals, its acute and chronic toxicity has been proven in many nontarget fish and insect species at low concentrations. The present study aimed to develop, validate, and test a more accurate method for ivermectin detection in various matrices (feces, soil, and sewage) for environmental studies. The method was validated using the Eurachem network. The applicability of the method was established at 1.5-500 μg/L for feces and 1.5-15 μg/L for sewage and soil. No dilution effect was observed at 5000 μg/L. The limit of detection was 0.66, 0.54, and 0.36 μg/kg for feces, soil, and sewage, respectively. The limit of quantification was set at 1.5 μg/kg and verified experimentally. Overall recovery was 92.27 ± 12.01% for feces and 96.19 ± 13.78% in soil, reaching a linearity of at least 0.99. The present method was successfully applied to 228 feces, 20 sewage, and 105 soil samples. This validated method enables the precise detection and quantification of ivermectin in the tested matrices, thereby envisaging potential applications in environmental monitoring studies with improved sensitivity and specificity.