Nanotechnology has engrossed researcher's interest over the decades due to its distinctive physicochemical properties and applications. Green synthesis is a multidisciplinary field and is rapidly developing because of its unique and rare properties such as non-toxic, clean and environmentally friendly, in distinction with physical and chemical methods of nanoparticle synthesis. Amongst the metal nanoparticles, iron has received greater attention due to its applications in biosensors, catalysis, wastewater treatment, and drug delivery. This review is dedicated to the biogenic synthesis of iron nanoparticles using plants and microorganisms, the technical procedures involved and characterization. The review converses important applications and future research approaches to improve the synthesis process. © 2020 Elsevier B.V., All rights reserved.