Graphene oxide (GO)/cellulose composite films were prepared by using an N-methylmorpholine-N-oxide (NMMO) monohydrate solvent. NMMO was an excellent dispersing agent for the GO as well as an environmentally friendly solvent for cellulose. The presence of a small amount of the GO significantly changed the rheological properties of the GO/cellulose/NMMO dope, and the thermal, electrical, and mechanical properties of the composite films. The viscosity of the GO/cellulose/NMMO dope increased significantly when a small amount of the GO was added into the dope. Thermal annealing of the composite films at 250°C removed the oxygen containing groups of the GO in the cellulose matrix and led to improvement of the electrical conductivity of the composite films. The interactions between the GO and cellulose made the composite films strong but brittle as a result of adding a small amount of the GO into the composite.