Reduced graphene oxide (rGO) has broad applications based upon its superior electronic properties. In many cases, an additional antibacterial function of these materials requests physical or chemical modification, such as incorporating silver nanoparticles into rGO to produce silver-reduced graphene oxide (Ag/rGO) composite. Most of the previous methods of preparing Ag/rGO are top-down techniques starting from graphite exfoliation into graphene oxide (GO), to the reduction of a mixture of silver nitrate and GO into the Ag/rGO nanocomposite. This method is flawed by its high cost, tedious treatments, and heavy pollution from generated wastes. Herein, we manifest a novel bottom-up strategy of growing Ag/rGO totally from a cellulose acetate and silver nitrate precursor in one step without tedious solution exfoliation and chemical treatment steps. The produced Ag/rGO nanocomposite maintains highly effective antibacterial activity, which is ascribed to the synergy between the effect of rGO size and incorporated bactericidal silver nanoparticles. Our strategy is promising for industrial production from sustainability and cost-effectiveness perspectives.