Exploring promising nanomaterials with high efficiency and robust stability holds paramount significance for addressing water crisis and water pollution. Herein, novel core-shell structured SiO2 @C-Ag nanocomposites were fabricated by one-pot Stöber method using resorcinol formaldehyde resins (RF) as a carbon source and silver ion as a catalyst and linker. Silver-ion–RF crosslinked frameworks were developed on silicon oxide cores through a coordination reaction, which was then transformed into metallic Ag nanoparticles impregnated in carbon frameworks after the carbothermal reduction. The resulting SiO2 @C-Ag nanocomposites exhibited enhanced catalytic performance for 4-nitrophenol reduction because of its increased specific surface area and abundant active sites. In addition, the well-dispersed Ag nanoparticles also offered excellent antimicrobial capability against Staphylococcus aureus and Escherichia coli. This work explores constructing multifunctional materials used as high-performance catalysts/bactericides for water purification.