Nanoporous oxides have been established as key materials for constructing electrodes for energy conversion and storage devices, offering high surface area and a large number of active sites for electrochemical reactions. Herein, we mainly focus on the characteristics, synthesis, and application of various nanoporous oxide electrodes for energy conversion and storage devices. Features of various nanoporous oxides by dimensionality and their functionalities in electrodes are presented. The synthesis strategies for nanoporous oxide electrodes to control their morphology are introduced, including top-down and bottom-up methods. Recent advances in nanoporous oxide electrodes in energy conversion and storage devices, such as fuel cells, water splitting electrodes, solar cells, light-emitting diodes, batteries, and supercapacitors, are summarized. The roles of nanoporous oxides tailored to the specific requirement for high performance of each device are further discussed. This review provides valuable insights into the design of nanoporous oxide electrodes from a materials point of view, contributing to renewable energy technologies.