Introduction: Soybean is one of the world’s major agricultural commodities and a cornerstone of the Brazilian economy. However, lepidopteran pests such as Helicoverpa armigera and Anticarsia gemmatalis can cause yield losses exceeding 30% and billion-dollar economic damage per growing season. In this context, the prospection of plant-derived insecticidal molecules combined with in silico approaches emerges as a promising and sustainable strategy. Methodology: Compounds from the heptane extract of Pyrostegia venusta flowers were previously identified, and their chemical structures were retrieved from public databases and optimized for computational analyses. Cytotoxicity was predicted in human cell lines (HEK-293, HEK-293T, HaCaT, and HUVEC) using quantitative structure–activity relationship models. Ecotoxicological assessment included predictions of bioconcentration factor (BCF) and aquatic toxicity toward Daphnia magna. Mechanisms of action were investigated through molecular docking against acetylcholinesterase (1QON), thioredoxin from A. gemmatalis (5DBQ), and farnesol dehydrogenase from H. armigera (7W61), using SwissDock and CB-Dock2 platforms. Commercial insecticides (flubendiamide and chlorantraniliprole) were used as reference compounds. Results: The natural compounds exhibited predicted cytotoxicity values ranging from pIC₅₀ 2.82 to 5.25 and bioconcentration factors between 0.35 and 1.25 Log₁₀(BCF). Predicted toxicity toward D. magna ranged from 2.42 to 4.13 LC₅₀ −Log₁₀(mol/L), lower than those of the synthetic controls. Docking analyses revealed stable interactions with ΔG values between −5.52 and −6.47 kcal/mol, highlighting allyl acetate and 2,2-dimethylpentanal. Conclusion: In silico analyses indicate that compounds from the heptane extract of Pyrostegia venusta exhibit relevant molecular affinity toward entomological targets and a favorable preliminary safety profile, supporting their potential as insecticidal candidates and warranting further in vitro experimental validation.