Deep eutectic solvents (DESs) have emerged as an eco-conscious, cost-effective, and highly versatile class of solvents, garnering significant interest because of their exceptional characteristics, such as low toxicity, conductivity, high solubility, and ease of recovery. These green solvents have shown tremendous potential as green alternatives to catalysts and conventional solvents in various chemical processes, including pharmaceutical production, biomass conversion, and organic synthesis. This chapter examines the role of DESs as green cosolvents and catalysts in diverse organic reactions, emphasizing advancements in homogeneous and heterogeneous catalysis and electrocatalysis over the past 5 years. This chapter is organized into three core sections: heterogeneous catalysis, homogeneous catalysis, and electrocatalysis. The chapter also highlights recent developments and key findings across various organic synthesis applications. Additionally, it discusses emerging trends and offers a forward-looking perspective on integrating DESs into catalytic systems for sustainable chemistry.