The population growth and the industrial revolution caused severe environmental pollution, especially pollution of clean water availability. Several ways have been conducted to overcome the pollution of clean water availability, one of which is by the adsorption of metal and cellulose-based waste materials as a hybrid catalyst. This study aims to fabricate and modify a hybrid catalyst composed of cellulose in the form of nanosized fibrils. Cellulose can be used as a catalyst by incorporating Fe from magnetite (Fe3O4) and can work effectively as an adsorbent for methylene blue (MB) dye waste. The method used in this research is a modified coprecipitation method by combining cellulose and Fe3O4 nanoparticles. Hybrid Catalyst of Fe3O4/Cellulose Nanocomposite-Base has been successfully characterized by using XRD, SEM-EDX, and UV-Vis, respectively to determine the particle structure, morphology, and adsorption capacity of the sample. The results of data analysis showed that Fe3O4/Cellulose could purify MB solution depending on the ratio of Fe3O4 and the mass of cellulose used. The higher the mass ratio of cellulose to Fe3O4, the absorbance value of the Fe3O4/Cellulose nanoparticle sample increases.