The excess use of chemical fertilizers creates residues in the agricultural produce, pollutes the environment, upsets the ecosystems, and deteriorates soil quality and health. Moreover, an excess amount of nutrients gets lost from the soil due to poor use efficiency and faulty methods of nutrient delivery. Controlled release of nutrients through a nanotechnological approach thus becomes cost-effective and efficient over conventional fertilizers. Nanofertilizers consist of one or more of the plant nutrients wherein at least more than 50% of the particles are smaller than 100 nm in size. Appropriate formulation of nanofertilizers tends to release the nutrients slowly in a steady state so that nutrients are released over an extended period. Apart from reducing nutrient loss and increasing nutrient use efficiency, nanofertilizers activate plant defense mechanisms against insects, pests, and other associated environmental stresses. Nanofertilizers hold the potential to improve environmental sustainability, but current research on the topic is mainly limited to controlled environmental conditions. Large-scale production, material availability, and appropriate field application logistics, especially in developing countries, are still lagging. Future research is needed to understand the long-term impact of nanofertilizers under field conditions, especially for major nutrients, in crop growth, soil quality, and overall environmental sustainability.