Nanoparticles are an important tool for new updations and advancements in diverse sectors. The inorganic metal and metal oxide nanoparticles have enormous research interest because of their great relevance in medicine, wastewater treatment, catalysis, biotechnology, and in the formation of energy storage devices. The NiO NPs can be synthesized using different physical and chemical methods and exploring all their possible applications. Green synthesis is the easy, safe, and effective nanoparticle synthesis route. Green metal and metal oxide nanoparticle syntheses provide the most affordable, convenient, and biocompatible approach for fabricating NiO NPs. This way is a good alternative to the conventional methods of synthesis. Green synthesis, being more constructive, is widely used in research and gives promising outcomes. This review highlighted the unique feature of the NiO nanoparticles. This paper brings forth the usage of green synthesis for synthesizing NiO nanoparticles. It also provides readers with a collective review of the recent development in the green synthesis of NiO NPs and their potential application in different fields.