Plant-mediated synthesis of nanomaterials has attracted considerable attention in recent years due to its cost-effectiveness and eco-friendly nature. In the present study silver and chitosan nanoparticles were successfully synthesized using Nerium oleander leaf extract as a bio-reducing agent. Results recorded from UV–vis spectrum, HRTEM and FTIR supported the biosynthesis and characterization of silver and chitosan nanoparticles. From HRTEM analysis, the AgNPs have spherical shape morphology with an average size of about 4-32 nm. CsNPs were ranged between 34-65 nm and the shape seem spherical with dark parts confirmed the capsulated plant extract. Larvicidal activity of leaf extract of N. oleander and synthesized silver and chitosan nanoparticles was carried out against M. domestica. CsNPs showed the utmost toxicity against M. domestica after 48h exposure with LC₅₀ value of 0.64 ppm and LC₅₀ values of leaf extract and AgNPs were 73.024 and 2.18 ppm respectively. A significant prolongation in the larval duration was observed in treated larvae. All the tested compounds induced reduction in the pupation rate and adult emergence and caused noticeable larval, pupal, and adult abnormalities. The potency in killing M. domestica larvae and stability of N. oleander-CsNPs have made this product a good candidate for the development of a novel natural larvicide.