In recent years, the use of cellulose fibers in many fields has attracted significant scientific attention due to consumer and environmentally benign, especially in plastic industry, which has been used as cost–cutting fillers and hence provides the possibility of reinforcing polymers. Cellulose can be extracted from natural fibers by chemical and mechanical methods. However, the existing procedures either produce low yields and not environment friendly or energy efficient. The objective of this study was to develop a novel process that uses ionic liquid followed by alkaline method to extract cellulose from empty fruit bunch (EFB) fiber. Subsequently, the properties of original fiber and cellulose were determined by Fourier Transform Infrared (FTIR) Spectroscopy, X–Ray Diffraction (XRD) and thermogravimetric (TG) analysis. The results of the chemical compositions revealed that the modified alkaline treatment was able to remove a large fraction of lignin and hemicelluloses compared to unmodified alkaline treatment. Thus, this process represents an efficient treatment in extracting cellulose of highest yield.