The application of nanotechnology in agriculture has emerged as a tool of great sustainable use for crop improvement. Pregerminative treatments with various chemicals and hormones are routine procedures to break the seeds' dormancy and stimulate crop germination. However, innovative techniques using nanoparticles (NPs) for seed priming are considered a potentially effective and efficient strategy to promote seed germination, nutrient delivery, and growth through impregnation. The present work aimed to synthesize iron oxide NPs (FeONPs) by a green method by using vegetal organic waste as a source of reducing and stabilizer agents for NPs formation, and then it was used to promote seed germination, growth, and biofortification of Solanum lycopersicum. The results indicate the effectiveness of orange peel waste for the one-step green synthesis of magnetite Fe3O4 NPs with an apparent spherical form and an average size of 13 nm determined with SEM analysis. The application of NPs as a nano priming (0.1-300 ppm) did not show significant changes in the germination development of tomatoes. However, positive effects on the growth of seedlings were observed with medium doses administered (10-50 ppm) because root length, stem length, and biomass were increased. In addition, an increase in the Fe and other micronutrients of both grain and seedlings was also observed, suggesting that nano priming with Fe3O4 NPs can stimulate the growth and Fe uptake of S. lycopersicum crops.