Activated carbon fiber (ACF) is widely used as an adsorption fiber in air purification systems. In this study, MgO and CuO nanoparticles were immobilized on ACF with enhancement of (3-aminopropyl)triethoxysilane (APTES). The obtained fibers' coating efficiency, structural deformation, and antimicrobial activities were investigated. The MgO-CuO/APTES/ACF fiber (DA-MC) sample showed high antimicrobial activity (<90%) against both Escherichia coli and Staphylococcus aureus after 24-hour treatment. DA-MC also showed the highest coating efficiency, with no observed structural deformation. The presence of APTES and curing step at high temperature is believed to increase the coating efficiency and thus result in the high antimicrobial activity and also protect the ACF from deformation.