Nanomaterials attract high research interest due to their favorable properties, such as high exposed surface area and higher bioavailability. Nanomaterial synthesis using chemical, physical, and biological methods includes process variables such as pressure, temperature, crystallization time, pH, solvents and surfactants, and mixing patterns in the synthesis media. These process variables and post-processing steps determine the uniformity of the synthesized nanomaterials and the degree of reproducibility of the nanomaterial synthesis protocol. Quality assurance aims to minimize the variability of the targeted properties of synthesized nanoparticles characterized using various techniques, including UV–vis, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and dynamic light scattering. Once the desired level of control of a particular synthesis is achieved, nanomaterials can be incorporated into products in various sectors including catalysis (oxide-supported Pt, Pd, Cu), agri-food (mesoporous silica, fullerene, Ag, ZnO), cosmetics (solid lipid nanoparticles, fullerene, TiO2, ZnO, Cu), lubricants and fuel additives (CeO2, MoS3), and nanomedicine and nanocarriers (Au, Ag, Fe, magnetic materials). This chapter highlights the current advances in quality assurance in nanomaterial synthesis, with special emphasis on metal NPs, process variables affecting quality control, statistical analysis of the nanomaterials to ensure their uniform properties and the prospects of nanomaterial quality assurance.