In today’s world of environmental fluctuations, plants can be exposed to many adverse environmental conditions. These environmental factors that cause stress in the plant can have serious consequences on the growth and development of the plant. Abiotic stress factors such as drought, salinity, heavy metal stress, and heat stress cause ionic and osmotic imbalance in the plant, causing a vital decrease in crop yield. In addition, weeds, nematodes, and pathogens that cause serious yield losses in plants are also known as biotic stress factors. Various chemical fertilizers, insecticides, pesticides, etc., are used to adapt plants to these adverse environmental conditions and to maintain food safety and agricultural production. However, given their environmental damage, more environmentally friendly and sustainable alternatives have been sought. Nanomaterials used in the field of nanotechnology can overcome the barriers in plants and reach the target tissue thanks to their physical and chemical properties. Nanoparticles are modern agricultural tools that help to increase growth and crop productivity in plants through the use of various nanoscale products such as nanofertilizers, nanotechnology, nanopesticides, nanoherbicides, and nanofungicides in agriculture. NPs can be applied to the plant in the form of root application, foliar spraying, and are transported to target sites in the plant through apoplastic and symplastic pathways. When beneficial NPs are transported to the target site in the plant, they help adaptation against biotic and abiotic stresses through physiological, biochemical, and molecular changes in the plant. Nanoparticles are also applied to plants using genetic engineering techniques in addition to classical methods. With the combination of nanobiotechnology and genome editing technology, CRISPR/Cas system, sustainability in agriculture is aimed at growing crops that are resistant to biotic and abiotic stress and have higher yields. Thus, it is hoped that crops obtained with nanoparticle-mediated genetic modification will meet the world’s food needs. In this chapter, different application areas of NPs in stress management and crop improvement, their application to plants, uptake, transportation, synthesis methods, and characterization topics will be reviewed.