Global agricultural systems are facing a number of unprecedented challenges. Nanotechnology is a useful tool for ensuring sustainability and increasing crop productivity in order to attain food security. Due to the unique properties of nanoparticles, such as their large surface area, reactivity, agglomeration, penetration capabilities, size, and structure, nanotechnology has made a wide range of applications in agriculture over time. When nanoparticles (NPs) are present in the soil, they can be taken up by the roots and migrate between and among the cells of the plant tissues after being adsorbed at the root surface. Additionally, through aerial deposition, NPs can be absorbed by plants, primarily via stomata and cuticles. Nanoparticles significantly influence plant growth and development by improving seed germination, facilitating nutrient delivery, enhancing tolerance to biotic and abiotic stresses, and promoting root and shoot growth. This chapter focuses on the types, modes of entry, uptake mechanisms, transport, interactions, and applications of nanoparticles in promoting plant growth.