Silver (Ag)-based materials are widely used as effective antibacterial agents for a wide spectrum of bacteria. There is a great challenge to reduce the amount of Ag in Ag-based materials without limiting its antibacterial activity. Herein, the Ag-zeolite NaY (50% from its cation exchange capacity) was functionalized with 3-aminopropyltriethoxysilane to produce an amine functionalized, Ag-zeolite NaY. The results showed that the functionalization of Ag-zeolite NaY improved its antibacterial activity against a wide spectrum of bacteria (Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538), especially in solutions containing electrolyte (saline solution), although it has a lower surface area, pore volume and amount of Ag released compared to those of zeolite NaY and Ag-zeolite NaY. Thus, the functionalization of Ag-based materials is a promising approach to reducing the amount of Ag required in Ag-based material while improving its antibacterial activity.