Zinc oxide/poly(vinyl alcohol) nanocomposite (ZnO/PVA) has unique structural and functional properties, leading to excellent potential in many electrical, optical, water treatment, and medical fields. According to the broad applications of this composite in different sciences, a comprehensive study of its various aspects is necessary. Based on our knowledge, no complete research has yet been carried out to address all its aspects. Then, in five major parts, this review study, then, investigated various aspects of the ZnO/PVA nanocomposite. In the "Introduction" section, ZnO nanoparticles, PVA polymer, and ZnO/PVA composite were illuminated. In this section, the ZnO/PVA composite was compared with some nanocomposites. The "properties" section examined the properties of the composite, such as optical, electrical, thermal, mechanical, and morphological properties. In the "synthesis" section, the synthesis methods of this composite and their instructions were discussed. The synergistic effect of ZnO and PVA on each other was thoroughly investigated in the same section. The "applications" section then detailed the applied aspects of ZnO/PVA composite, ranging from water treatment to the medical field. Many research efforts have been made to address the inherent shortcomings of this nanocomposite. In the "modification" section, an overview was done on several materials (including metal, metal oxide, carbon, and natural and synthetic polymers), used to design an appropriate and logical ZnO/PVA modification to form a better structure. It is expected that this overview would offer useful information for researchers in different fields, such as measurement, electromagnetic protection, water treatment, energy storage, and medical science.