Nanotechnology has changed and developed all the sectors and working fields. Nanoparticles are one of the important evolutionary materials that have application in almost all the working areas such as catalysis, bioengineering, photoelectricity, antibacterial, anticancer, and medical imaging due to their unique physical and chemical properties. Traditionally used chemical and physical method of synthesis of nanoparticles have several disadvantages like using different chemicals, high cost, and most importantly they are hazardous to the environment. Counter to these disadvantages, a more eco‐friendly, easy, and cost‐effective green synthesis method is widely employed nowadays. Various parts of a plant are used as a fuel for reducing the metal ion salt. Plant extracts act as reducing, stabilizing, and capping agents. Besides these advantages, photosynthesized nanoparticles are nontoxic, more stable, and more uniform in size than their counterparts prepared by the traditional method. In this present review, the synthesis of various plant extract‐mediated metal and metal oxide nanoparticles is discussed along with their different applications. This review provides a comprehensive overview of key findings in green synthesis of metal and metal oxide nanoparticles and attempts to determine their possible synthesis mechanism. This article also focuses on factors affecting their synthesis, characterization, potential applications, and prospects.