The Reprint "Ionic Liquids and Deep Eutectic Solvents: Greener Approaches for Sustainable Chemistry" is based on the selection of contributions to the topical Special Issue and aims to provide a comprehensive overview of the "state of the art" and the remarkable advances in the field of the two classes of unconventional, i.e., green solvents. The broad scope and diverse approaches make it interesting for researchers to learn more about sample preparation of various complex matrices (natural and food products, biomass, pharmaceuticals, etc.), extraction of targeted bioactive compounds, essential molecules, and pollutants, biomass and nanocomposite-based adsorption technologies for reuse, water treatment and pollutant removal, as well as IL- and DES-based green synthesis, catalysis, and improvement of chemical and technological processes. The latest findings on recycling and recovering more environmentally friendly solvents, the use of advanced analytical techniques and methods, and adherence to green chemistry principles will be fully recognized.