The surface of polypropylene (PP) fiber was modified by UV-induced graft polymerization of 1-vinylimidazole (Vim), followed by quaternization with iodomethane, sulfonation with chlorosulfonic acid, or loading of silver (Ag) nanoparticles to endow the surface with antibacterial properties. The modified PP fibers were characterized by FT-IR, SEM, and surface charge analyses. The antibacterial activity of the modified PP fibers was assessed against the Gram-negative and Gram-positive bacteria, Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus), respectively. The PP-g-Vim was greatly improved by loading of Ag nanoparticles (≥99.9%), quaternization (98.9-99.2%), or sulfonation (≥99.9%).