By 2023, it is predicted that the world’s energy consumption will increase by up to 50%, with crude oil remaining the main energy source. Despite significant advances, conventional oil recovery methods yield only about one-third of the reservoir's oil, necessitating the development of new Enhanced Oil Recovery (EOR) techniques. Among these, Chemical EOR has gained considerable attention which involves the injection of certain chemicals to improve the mobility ratio, reduce Interfacial Tension (IFT), and alter rock wettability. However, the low sweep efficiency, high costs, and possibility of formation damage associated with conventional Chemical EOR limit their broader application. According to recent research, nanoparticles (NPs) hold promise in overcoming these limitations. Due to their nanoscale size (<100 nm) and large surface area, NPs can significantly alter subsurface properties when used in EOR applications. They can pass through the permeable paths of the porous media owing to their stable dispersion in nanofluid, which improves the oil recovery in a number of ways. Their ability to be dispersed stably in nanofluid allows them to flow through the porous media, enhancing oil recovery through various mechanisms. These mechanisms include increasing disjoining pressure, plugging pore channels, raising the nanofluid viscosity, controlling fines migration, decreasing oil-nanofluid IFT, altering rock wettability, and preventing asphaltene precipitation. This chapter reviews the application of nanoparticles in Chemical EOR in sandstone reservoirs. The review highlights how nanoparticles can be used to improve the drawbacks of traditional Chemical EOR techniques, providing a more economical and effective means of optimizing oil recovery. As the availability of conventional oil resources continues to decline, the use of nanoparticle-assisted EOR is essential to meet the future energy demand. This comprehensive review aims to provide insights into the formation of nanoparticles, mechanisms behind nanoparticle-assisted EOR and their role in the sustainable development of hydrocarbon resources.