This chapter describes the use of deep eutectic solvents (DESs) for the extraction of phytochemicals and their application in medicinal formulations. The theoretical basis of DESs, including their solvent properties such as melting point, viscosity, and polarity, is discussed, and their mechanisms of action in extraction techniques such as microwave-assisted and ultrasound-assisted extraction are explored. Furthermore, this review focuses on the use of DESs in pharmaceutical production. Specifically, their application in drug delivery systems and formulations, as well as their capacity to improve the solubility and bioavailability of pharmaceuticals with low water solubility, has been explored. Additionally, the chapter discusses techniques for enhancing DES-based extraction procedures, such as scalability and energy consumption, in comparison with traditional methods. Both hydrophilic and hydrophobic DESs benefit extraction procedures and the extraction of target molecules. This chapter provides a detailed analysis of DESs in comparison with traditional solvents and ionic liquids, focusing specifically on their environmentally sustainable characteristics. This review discusses the utilization of DESs as solvents for ready-to-use extraction and highlights their ability to increase the efficiency of both the extraction and manufacturing of pharmaceutical formulations.