Parasitic nematodes, such as the zoonotic rat lungworm Angiostrongylus cantonensis, pose a significant global health burden, with current anthelmintics like albendazole showing limited efficacy. Here, we report the isolation of piplartine from Piper truncatum Vell. (Piperaceae) and its potent in vitro activity against A. cantonensis larvae. Piplartine demonstrated superior efficacy to albendazole, with EC₅₀ values of 8.3 µM for first-stage larvae (L1) and 10.4 µM for infective third-stage larvae (L3), compared to 14.2 µM (L1) and 15.6 µM (L3) for albendazole. Notably, piplartine exhibited no toxicity in the Caenorhabditis elegans model at therapeutic concentrations, underscoring its selective antiparasitic action. In silico profiling further revealed favorable drug-likeness and pharmacokinetic properties, including high gastrointestinal absorption and blood–brain barrier permeability, which are critical for targeting neurotropic infections. As the first study to characterize the activity of piplartine against A. cantonensis, our work highlights its potential as a structurally novel anthelmintic lead. Based on the obtained results, piplartine may be considered a promising and accessible candidate for combating angiostrongyliasis and related helminthic infections.