This review article presents recent advances on the use of electrospun nanofibers as nanoreactors to synthesize various organic/inorganic hybrid nanomaterials consisting of a polymeric matrix hosting in situ generated inorganic nanoparticles (NPs) for different applications. Electrospun nanofibers possess attractive properties such as controllable fiber diameters, high aspect ratio, and high surface area to volume ratio, affording their uses as a unique nanoreactor system to fabricate a range of organic/inorganic hybrid nanomaterials. In particular, the nanohybrids consisting of metal, metal oxide, metal sulfide, or metal chloride NPs can be in situ generated within the polymeric fiber matrix via different reactions such as UV and microwave irradiation, chemical reduction, heating treatment, and galvanic replacement reaction. The formed organic/inorganic hybrid nanomaterials have been used for environmental remediation, catalysis, electronic and sensing devices, energy, wound dressing, etc. Some of the key developments in this area of research will be introduced in detail. (C) 2018 Elsevier B.V. All rights reserved.