The present Review opens with an overview of metal oxides and the description of their material properties. The first part mainly deals with various preparation techniques and growth mechanisms, which have been largely developed in the last few decades to fabricate different types of metal oxide nanostructures. The second part, on the other hand, will provide the Reader with an up-to-date summary of different applications in which metal oxides nanostructures have been successfully implemented and/or suggested. In particular, great attention will be dedicated to the implementation of metal oxide nanostructures for gas sensing as well as light emission applications, for which both working principles and integration, as well as the latest reported cutting edge results are herein reported. Finally, we emphasize on the current potentials of metal oxide nanostructured materials and future challenges that this field in continuous expansion is currently facing.