Ionic liquids (ILs) as a class of materials that are composed of cations and anions have been attracted much attention and used in a variety of applications. Due to the negligible volatility, high chemical and thermal stability, high ionic conductivity and wide electrochemical window, ILs have been used in the electrochemical devices, electrocatalysis, extraction, electrosynthesis, gas absorption and sensors. In addition to the application in electrochemical devices, ILs have been used in energy transformation devices. Therefore, in this review, we have focused on mainly the applications of ILs in electrochemical energy storage, energy conversion and CO2 reduction. We also discuss the current trend of computational design for ILs electrochemical system and IL-like ion conductor from nature, which could be employed in green electrochemistry applications in the future.