Gemini ionic liquids (ILs) are usually known to have significant surfactant behavior. Nanomaterials, on the other hand, are capable of improving interface properties. The current study explores the use of a novel nano gemini imidazolium IL with a molecular structure of a four methylene group spacer for reducing crude oil/water interfacial tension (IFT). The gemini IL was prepared purely by a two-step synthesis method and characterized in different ways. Results revealed that IFT was drastically decreased to 97.8% in the presence of the IL and more decrease was achieved with temperature and pH variations. The high performance of the IL can be attributed to the strong IL amphiphilic nature. The salt effects in the presence of the IL were evaluated with NaCl, MgCl2, and their mixture. Results revealed more IFT reduction under salinity conditions because of a remarkable found synergism effect, unlike conventional surfactants. The findings encourage the use of seawater IL solutions in chemical enhanced oil recovery. The obtained salt-free IFT data were precisely reproduced with the well-known Frumkin adsorption isotherm, and the corresponding thermodynamic parameters were obtained at different temperatures. From thermodynamic results, a spontaneous IL adsorption was deduced.