In contemporary society, there has been a notable increase in the application of functional materials such as ionic liquids, nanofluids, and nanomaterials across diverse disciplines. Ionic liquids are characterized as a subset of low-melting-point salts that exhibit minimal volatility and flammability. Due to their distinctive attributes, including thermal stability and tunable viscosity, these environmentally friendly solvents are employed as electrolytes in energy storage systems, separation technologies, and biomass processing. Nanofluids, which consist of nanoparticles dispersed within base fluids, possess exceptional rheological, thermophysical, and optical properties. They are utilized in various applications, including cooling systems, heat transfer, solar energy systems, and microelectronics. Another category of materials, nanomaterials, which includes nanoparticles, dendrimers, quantum dots, and nanocomposites, demonstrates remarkable surface area and superior electrical, optical, and thermal characteristics; these materials are applicable in energy storage devices, water purification systems, and the medical sector. The extensive domain of nanotechnology leverages these functional materials to develop novel classes of materials with enhanced properties and applications. This chapter seeks to elucidate these interconnected domains, their synergies, and their applications in ongoing research and development endeavors.