Ionic liquids are salt-like compounds that remain in a liquid state at low temperatures and that have their melting points below 100°C. After the discovery of the first ionic liquid, ethylammonium nitrate, by Paul Walden in 1914, it took almost a century for ionic liquids to gain researchers� attention. In the past two decades, ionic liquids have been witnessed as green solvents and received high importance as substitutes for conventional organic solvents contributing to the principles of green chemistry. Considering the superior advantages of ionic liquids, they have been employed in numerous applications over the past few years. This chapter demonstrates the most sustainable applications of various ionic liquid-based materials. Prior to this, however, the chapter outlines the background of the study following key properties and implications of common ionic liquids. Finally, concluding remarks and future perspectives that are expected to appear in various future applications are provided. © 2022 Elsevier Inc. All rights reserved.