<p>Considering the reduced environmental impact and high specificity in targeting vector organisms, the use of plant-based insecticides for dengue mosquito control is crucial in dengue disease management. We investigated the larvicidal efficacy of hot water, cold water, and water-acetone extracts of combined plant extracts of <i>Capsicum frutescens</i> (Naimiris) and <i>Allium sativum</i> (Garlic) against <i>Aedes aegypti</i> and <i>Aedes albopictus</i> larvae. The plant extract encapsulated chitosan nanoparticles were also assessed for larvicidal potential. Chitosan nanoparticles were synthesized via the ionic gelation method, employing an optimized formulation comprising 2.5% chitosan and 1.5% sodium tripolyphosphate, with stirring at 1500&#xa0;rpm. The most effective plant extract was encapsulated into chitosan nanoparticles, which were subsequently packaged into commercially viable sachets. The water-acetone extract showed the highest larval mortality, resulting in the lowest LC₅₀ values (2051.01 and 1097.69 mg L^-1 after 24 and 48&#xa0;h of exposure, respectively), while showing the significant synergistic activity (CI &lt; 1). Nanoparticle characterization was conducted using Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy, revealing a nanoparticle diameter ranging from 350 to 450&#xa0;nm. Approximately 96.10 ± 2.77% of combined plant mixture’s water-acetone extract was successfully encapsulated within nanoparticles, with 90% of encapsulated plant extract released into the medium over a 14-day period. Semi-permeable sachet packets containing 6&#xa0;g of encapsulated chitosan nanoparticles showed strong larvicidal activity for 10 days, with a shelf life up to six months. These findings suggest that chitosan nanoparticles encapsulating a combination of <i>Capsicum frutescens</i> and <i>Allium sativum</i> extracts demonstrate strong potential as eco-friendly larvicides against dengue vectors.</p> Graphical Abstract <p></p>