Introduction: Bacterial infections caused by different strains of bacteria still one of the most important disorders affecting humans worldwide. Polymers nanocomposite systems could be considered as an alternative to conventional antibiotics to eradicate bacterial infections. Significance: In an attempt to enhance the antibacterial performance of silver and iron oxide nanoparticles, decrease their aggregation and toxicity, a polymeric hybrid nanocomposite system combining both nanoparticles is produced. Methods: Magnetic Ag–Fe3O4@polymer hybrid nanocomposites prepared using different polymers, namely polyethylene glycol 4000, ethyl cellulose, and chitosan were synthesized via wet impregnation and ball-milling techniques. The produced nanocomposites were tested for their physical properties and antibacterial activities. Results: XRD, FT-IR, VSM, and TEM results confirmed the successful preparation of hybrid nanocomposites. Hybrid nanocomposites have average crystallite sizes in the following order Ag–Fe3O4@CS (8.9 nm) < Ag– Fe3O4@EC (9.0 nm) < Ag–Fe3O4@PEG4000 (9.4 nm) and active surface area of this trend Ag–Fe3O4@CS (130.4 m2 g−1 ) > Ag–Fe3O4@EC (128.9 m2 g−1 ) > Ag–Fe3O4@PEG4000 (123.4 m2 g−1 ). In addition, they have a saturation magnetization in this order: Ag–Fe3O4@PEG4000 (44.82 emu/g) > Ag–Fe3O4@EC (40.14 emu/ g) > Ag–Fe3O4@CS (22.90 emu/g). Hybrid nanocomposites have a pronounced antibacterial action against Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus intermedius compared to iron oxide nanoparticles and positive antibacterial drug. In addition, both Ag–Fe3O4@EC and Ag–Fe3O4@CS have a lower MIC values compared to Ag–Fe3O4@PEG and positive control. Conclusion: Magnetic Ag–Fe3O4 hybrid nanocomposites could be promising antibacterial nanomaterials and could pave the way for the development of new materials with even more unique properties and applications.