Nowadays nanotechnology is a buzzword in scientific area with diverse number of applications. The advancement in the eco-friendly and reliable systems for the development of nanoparticles are a crucial key to the discipline of nanotechnology. Nanoparticles have been incessantly evaluated and utilized in numerous industrial applications. Specifically, the rule of cobalt oxide nanoparticles has received an incredible interest due to its, UV filters properties and photochemical, antifungal, high catalyst, and antimicrobial activities. In chemical and physical techniques High rate of harmful chemicals are used for the synthesis of nanomaterials. To overcome this issue various clean and green methods are adopted which use plants, organisms and microscopic organisms for the synthesis of nanoparticles. This paper reviews different green synthesis techniques used for synthesis of cobalt oxide NPs and their applications. It was found that, the green route of synthesis is safe and eco-friendly. Additionally it is expected that the biomedical applications in this area will expand in different procedures including bio imaging, drug delivery, biosensors, and gene delivery. Also, cobalt oxide NPs can act about as sharp weapons against numerous drug resistant microorganisms and as a gifted substitute for antibiotics.