Larvicides are a class of insecticides that chemically control the growth of dengue vectors. Although synthetic larvicides remain effective for mosquito control, their prolonged and excessive use may contribute to insecticide resistance and potential environmental impacts. In alternative literature, silver nanoparticles can be used to reduce these negative impacts, as they exhibit larvicidal activity. Organic waste, such as plumeria leaves that have fallen, wilted, and lost economic value, can serve as a bioreductor in the synthesis of silver nanoparticles. Green synthesis of silver nanoparticles was carried out by mixing the water extract of plumeria leaves with a 1 mM AgNO3 solution at a 1:9 (v/v) ratio. The concentration of the plumeria leaf water extract used was 1%, and the heating temperature was 60°C. Silver nanoparticles were characterized using a UV-Vis spectrophotometer, PSA, TEM, and SEM-EDS, and their larvicidal activity was tested. Silver nanoparticles provide a maximum wavelength of 430 nm. The TEM and SEM-EDS characterization results show irregular spherical shapes, as well as square and triangular shapes, and PSA confirmed an average particle size of 72.39 nm with a zeta potential of −21.51 mV. Biosynthesized silver nanoparticles exhibit larvicidal activity with an LC50 of 13 ppm.