Most nanoparticles have diameters that lie within 1 to 100 nm. A variety of metal oxide nanoparticles can be synthesised chemically as well as biologically. NiO nanoparticles, which are synthesised chemically, tend to be highly toxic in their effects. In contrast, synthesis by the route of biogenesis or biomimetics is much more favourable than chemical synthesis. The pre-existing properties of purple cabbage are remarkably enhanced by NiO nanoparticles. Nickel oxide (NiO) nanoparticles were synthesised from the leaves of Brassica oleracea var. capitata. f. rubra (purple cabbage) by reducing Nickel nitrate hexahydrate solution for the formation of NiO nanoparticles. The analysis done using a Particle size analyser reveals the spherical morphology and the size of the NiO nanoparticles. The size and shape were studied under a Scanning Electron Microscope, which shows that the nanoparticle ranges from 34.5 nm to 89.6 nm. The formation of NiO nanoparticles was confirmed by the peaks obtained in Raman spectroscopy and UV-DRS analyser. The peaks that ensure the formation of NiO nanoparticles in Raman spectroscopy are 568.40 cm-1, 1129.46 cm-1 and 1379.07 cm-1 and UV-DRS are 265.60 nm and 339.69 nm. Preliminary phytochemical analysis of the aqueous extract of purple cabbage leaves shows that there is an abundance of phytochemical content present in purple cabbage. From the preliminary phytochemical analysis of purple cabbage, it was observed that the aqueous purple cabbage leaf extract contains alkaloids, sterols, flavonoids, coumarin, tannins, cardiac glycosides, anthraquinones, saponins, quinones, and carbohydrates.