Nanotechnology has undergone significant advancements since the 1980s, leading to a surge in nanobased synthesized and marketed products. This technology holds substantial promise across various sectors, including biomedicine, pharmaceuticals, farming, and the agrofood industry. The foundation of nanotechnology lies in nanoparticles, which are in the range of 1–100 nm. NPs are categorized as inorganic, organic, ceramic, or carbon-based, with inorganic NPs being subdivided into metal and metal oxide types. Nanoparticle synthesis generally uses two major approaches: top-down and bottom-up methods. This review covers chemical, physical, and eco-friendly synthetic methods. In addition, qualitative and quantitative characterization techniques were used. Qualitative methods include Fourier transform infrared spectroscopy (FT-IR), UV‒Vis spectrophotometry, scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM), whereas quantitative techniques include transmission electron microscopy (TEM), high-angle annular dark-field imaging (HAADF), and inductively coupled plasma (ICP) analysis. This review examines various nanoparticle production methods and their applications, focusing on the increasing role of nanotechnology in agriculture and biomedicine, which directly and indirectly impacts human health. Given the broad scope and complexity of these applications, further research is essential to clarify the mechanisms involved and determine which safe nanomaterials may be viable for market introduction.