Nanoparticles refer to ultrafine particles with the particle size at nanoscale. When metals and metal oxides were synthesized at nanoscale, by their unique properties such as smaller particle size, high strength, reactivity, sensitivity, specificity and stability, they have established a wide variety of applications, and thus have gained popularity in various industries such as food, textile, cosmetic, automobile and pharmaceuticals. Silver, gold, copper, aluminium, nickel, iron, zinc oxide, titanium dioxide and copper oxide nanoparticles are few among them. This article presents a review on zinc oxide nanoparticles, its green synthesis methods and various applications in biomedical fields such as antibacterial, antifungal, anticancer, anti-inflammatory and wound healing.