Modern agriculture and human nutrition depend on the use of agrochemicals. Among these are pesticides and synthetic fertilizers that cause a significant impact on ecosystems. It is desirable, therefore, to have alternatives that without reducing the production of food and its quality, reduce the amount and variety of pesticides and synthetic fertilizers used. Nanosilicon and nanochitosan are attractive materials due to their low environmental impact and their ability to induce positive responses in soils and plants. Compared with bulk materials, the use of nanometric materials significantly increases their effectiveness. The application of nanosilicon and nanochitosan to the soil, either individually or in combination, increases the bioavailability of mineral nutrients, reducing the need to apply copious amounts of fertilizers. On the other hand, the adverse effects of salinity, water deficit, heavy metals, and root pathogens are mitigated, reducing the need for pesticide use and increasing tolerance to environmental stress in plants. When applied by foliar spraying, the impacts of nanosilicon and nanochitosan are equally positive, functioning as biostimulant compounds that induce and strengthen the defense mechanisms of plants against biotic and abiotic stresses, in addition to increasing their nutritional quality. The result obtained is a combination of stronger crops and an edaphic system that supports more productive plants. This chapter presents updated information about the agricultural application of nanosilicon and nanochitosan with the objective of reducing the use of pesticides and synthetic fertilizers, mitigating the environmental impact of agricultural activity.