The extensive usage of conventional chemical fertilisers in agriculture to enhance crop yields has subsequently led to many unintended effects, such as water and air pollution and soil quality degradation. For this reason, innovative technologies such as nanotechnology have emerged to help produce quality and sufficient food sustainably for the ever-growing world population. Nanotechnology, as the science of the production of nanoparticles with a size less than 100 nm has been adopted among other solutions. Nanoparticles can play a vital role in enhancing plant nutrition use efficiency, protection development, and yield. Nanoparticles are applied in small quantities due to their sizes, thus reducing the risk of leaching and unintended release in the environment. The synthesis of nanoparticles is traditionally done through chemical and physical methods that involve toxic chemicals, which can also lead to detrimental effects on the environment in the long run. Thus, biosynthesis using living systems such as plant extracts, fungi, and algae has equipped nanoparticles with their eco-friendliness and cytocompatibility, which are key for their usage in the field of agriculture as nanofertilisers for targeted delivery of several minerals that are hard to supply using conventional methods. Although their mechanism of action is not yet well understood, their benefits have been highlighted in several studies that have reported beneficial effects of several nanoparticles such as calcium carbonate, magnesium oxide, copper oxide, iron oxide, and zinc oxide in increasing tomato, chickpea, groundnut and soybean growth, yield, and fruit quality. Therefore, this chapter focuses on the use of green synthesised nanoparticles for plant fertilisation.