This study explored the green synthesis and immobilization of colloidal silver nanoparticles (AgNPs) on a solid compatible support. Its antibacterial properties in reusable air filters are also discussed. The chitosan stabilized colloidal AgNPs (chi-AgNPs) were prepared using visible light irradiation in methanol. The UV–Vis, FTIR spectra, and TEM confirmed the chi-AgNPs formation. The immobilization technique of chi-AgNPs on the surface of white-silica-gel beads, which was previously coated chitosan (chi-SiG), was effective. The immobilized silver particles (AgNPs-[chi-SiG]) were solid, stable, dispersed, and nano-size. Both AgNPs-[chi-SiG] and chi-SiG exhibited antibacterial properties and prevented the growth of Gram-positive ( Staphylococcus aureus ) and Gram-negative ( Escherichia coli ) bacteria in agar media. Air filter containing the AgNPs-[chi-SiG] showed high antibacterial activity against Bacillus subtilis in the air.